US Midwives' Knowledge and Use of Sterile Water Injections for Labor Pain

Lena Märtensson, CNM, PhD; Maureen McSwiggin, CNM, MS; Judith S. Mercer, CNM, DNSc

J Midwifery Womens Health. 2008;53(2):115-122.

Abstract and Introduction

Abstract

The purpose of this research study was to identify and describe US midwives' knowledge and use of sterile water injections to relieve pain during labor. Research studies have shown that injections of sterile water to relieve low back pain during labor are effective with good maternal satisfaction. However, no knowledge is available about their use by midwives in the United States. Questionnaires were mailed to a random sample (N = 450) of midwives who were members of the American College of Nurse-Midwives (ACNM). One hundred thirty-two respondents (29%) returned the questionnaire. One-fourth (26%) of the midwives use sterile water injections, although infrequently. More than half of the midwives use the intracutaneous injection technique, and most use a total of four injections. Most midwives give the injections between contractions, with the assistance of another person, and report very good pain relief. Of those not using sterile water injections, most had no experience or training in use of the method and were interested in learning more about their use. While sterile water injections are a good treatment for back pain during labor, there is a lack of knowledge among midwives about this method of pain relief during labor and an interest in knowing more.

Introduction

For most of the approximately 4 million women who give birth annually in the United States, labor pain is an issue of concern. The intermittent uterine contractions needed to expel the fetus from the uterine cavity dilate the cervix, causing pain that can radiate to the lower abdomen and/or the lower back (sacral area). Approximately 25% of laboring women experience back pain. For women who want to labor without an epidural, the back pain can be severe enough to undermine their intentions. Sterile water injection can offer significant relief from back pain in labor without concerns that the method might harm the mother and/or the fetus or slow the labor pattern.^[1] The Gate Control Theory is proposed as the most plausible mechanism of action.^[2] Despite these benefits, there is no information available regarding US midwives' use of sterile water injections during labor. The aim of this study was to identify and describe US midwives' knowledge and use of sterile water injections for pain relief during labor.

1 2 3 4 5 6

Next Section

Abstract and Introduction
Background
Methods
Results
Discussion
Conclusion
References
Appendix: Sample Procedural Guidelines for Sterile Water Injections

Table 1. Summary of Studies of Sterile Water Injections as Relief for Labor Pain
Study (Year)	Objective	Inclusion Criteria	Design	Instrument	Results
Bahasadri et al. (2006)^[10]	To evaluate the efficacy of SC sterile water injection in reduction of labor pain compared with placebo	First stage of labor; planned normal vaginal delivery	RCT, Intervention group (n = 50) 1 x 0.5 mL sterile water injection SC; Control group (n = 50) 1 x 0.5 mL saline SC	Face rating scale	The median pain score in the sterile water group was significantly lower than the placebo group at 10 min, as well as 45 min, after the injection
Wiruchpongsanon (2006)^[17]	To study the effectiveness of IC injection of sterile water in relieving low back pain during labor in Thai women	Pregnant women (wks 37-42); active first stage of labor; low back pain	RCT, Treatment group (n = 25) 4 x 0.1 mL sterile water IC; Placebo group (n = 25) 0.1 mL saline IC	VAS	Mean pain reduction was significantly greater in the treatment group compared to the placebo group at 30 min, 1 and 2 hours after injection (P < .001)
Märtensson et al. (2000)^[3]	To investigate whether, during injections of sterile water, there is any difference in perceived pain between IC and SC injections	Women aged 18-45 years; not pregnant; no pain conditions experienced during the trial	RCT, Cross-over design: group 1 (n = 50); group 2 (n = 50); all women were given both IC and SC injections in randomized order	VAS	IC injections of sterile water showed to be significantly more painful than SC injections even when trial, day and injection location were taken into consideration (P < .001)
Märtensson and Wallin (1999)^[14]	To evaluate relief of pain in labor with SC and intracutaneous injections of sterile water vs placebo	Pregnant women (wks 37-42); first stage of labor; severe lower back pain	RCT, Treatment group 1 (n = 33) 4 x 0.1 mL sterile water IC; Treatment group 2 (n = 33) 4 x 0.5 mL sterile water SC; Placebo group (n = 33) 4 x 0.1 mL saline SC	VAS	The pain reduction was significantly greater in both treatment groups compared to placebo at 10 and 45 min after treatment
Labrecque et al. (1999)^[12]	To compare sterile water injections and TENS for low back pain during labor	Pregnancy (wk > 36); low-risk; active first stage of labor; low back pain	RCT, Group 1 (n = 11) 4 x 0.1 mL sterile water IC; Group 2 (n = 12) TENS; Group 3 (n = 12) standard care (bath, massage, mobilization)	VAS	Sterile water injections are more effective than standard care and TENS for low back pain
Dahl and Aarnes (1991)^[11]	To reevaluate the method and factors possibly influencing its efficacy	Healthy women; pregnant (wks 38-42); single gestation	Group 1 (n = 101) 2-4 injections of sterile water IC; group 2 (n = 50) dry needle injections; group 3 control group (n = 117) conventional treatment; lumbosacral and/or suprapubic injections used	VAS ungraded 0 = no pain, 10 = unbearable pain	Sterile water papules provided better relief for labor pain in the IC group compared with the dry needle group; early treatment yielded best effect
Trolle et al. (1991)^[15]	Evaluate the analgesic effect of intradermal sterile water block for back pain during labor	Active labor; back pain	RCT, Study group (n = 141) 4 x 0.1 mL sterile water IC; Control group (n = 131) 4 x 0.1 mL NaCl IC; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	Significantly greater reduction of VAS score in the sterile water group compared with the NaCl group, up to 90 min after treatment
Ader et al. (1990)^[9]	Investigate the efficacy of sterile water papules for back pain during labor	Pregnant (wk ≥ 37); first stage of labor; back pain; pain relief required	RCT, Study group (n = 24) 4 x 0.1 mL sterile water IC; control group (n = 21) 4 x 0.1 mL NaCl SC; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	Significantly increased reduction of VAS score in the sterile water group compared with the NaCl group; analgesic effect up to 90 min
Lytzen et al. (1989)^[13]	Evaluate if sterile water papules can be an alternative for alleviating back pain	Established labor	Study group (n = 83) 4 x 0.1 mL sterile water IC; lumbosacral injection were given	VAS; ungraded 0 = no pain, 10 = unbearable pain	VAS score reduced significantly 3 hours after injection compared with just before administration
Trolle et al. (1986)^[16]	Evaluate if back pain during labor can be treated with IC sterile water papules	Primipara; pregnancy (wk ≥ 37); cervix dilatation ≤4 cm	RCT, Study group (n = 38) 4 x 0.1 mL sterile water IC; Control group (n = 38) no treatment; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	The treatment group experienced significantly better pain relief compared with the control group, up to 60 min after treatment

IC = intracutaneous; ID = intradermal; NaCl = sodium chloride; RCT = randomized controlled trial; SC = subcutaneous; TENS = transcutaneous electrical nerve stimulation; VAS = visual analog scale.

Table 1. Summary of Studies of Sterile Water Injections as Relief for Labor Pain
Study (Year)	Objective	Inclusion Criteria	Design	Instrument	Results
Bahasadri et al. (2006)^[10]	To evaluate the efficacy of SC sterile water injection in reduction of labor pain compared with placebo	First stage of labor; planned normal vaginal delivery	RCT, Intervention group (n = 50) 1 x 0.5 mL sterile water injection SC; Control group (n = 50) 1 x 0.5 mL saline SC	Face rating scale	The median pain score in the sterile water group was significantly lower than the placebo group at 10 min, as well as 45 min, after the injection
Wiruchpongsanon (2006)^[17]	To study the effectiveness of IC injection of sterile water in relieving low back pain during labor in Thai women	Pregnant women (wks 37-42); active first stage of labor; low back pain	RCT, Treatment group (n = 25) 4 x 0.1 mL sterile water IC; Placebo group (n = 25) 0.1 mL saline IC	VAS	Mean pain reduction was significantly greater in the treatment group compared to the placebo group at 30 min, 1 and 2 hours after injection (P < .001)
Märtensson et al. (2000)^[3]	To investigate whether, during injections of sterile water, there is any difference in perceived pain between IC and SC injections	Women aged 18-45 years; not pregnant; no pain conditions experienced during the trial	RCT, Cross-over design: group 1 (n = 50); group 2 (n = 50); all women were given both IC and SC injections in randomized order	VAS	IC injections of sterile water showed to be significantly more painful than SC injections even when trial, day and injection location were taken into consideration (P < .001)
Märtensson and Wallin (1999)^[14]	To evaluate relief of pain in labor with SC and intracutaneous injections of sterile water vs placebo	Pregnant women (wks 37-42); first stage of labor; severe lower back pain	RCT, Treatment group 1 (n = 33) 4 x 0.1 mL sterile water IC; Treatment group 2 (n = 33) 4 x 0.5 mL sterile water SC; Placebo group (n = 33) 4 x 0.1 mL saline SC	VAS	The pain reduction was significantly greater in both treatment groups compared to placebo at 10 and 45 min after treatment
Labrecque et al. (1999)^[12]	To compare sterile water injections and TENS for low back pain during labor	Pregnancy (wk > 36); low-risk; active first stage of labor; low back pain	RCT, Group 1 (n = 11) 4 x 0.1 mL sterile water IC; Group 2 (n = 12) TENS; Group 3 (n = 12) standard care (bath, massage, mobilization)	VAS	Sterile water injections are more effective than standard care and TENS for low back pain
Dahl and Aarnes (1991)^[11]	To reevaluate the method and factors possibly influencing its efficacy	Healthy women; pregnant (wks 38-42); single gestation	Group 1 (n = 101) 2-4 injections of sterile water IC; group 2 (n = 50) dry needle injections; group 3 control group (n = 117) conventional treatment; lumbosacral and/or suprapubic injections used	VAS ungraded 0 = no pain, 10 = unbearable pain	Sterile water papules provided better relief for labor pain in the IC group compared with the dry needle group; early treatment yielded best effect
Trolle et al. (1991)^[15]	Evaluate the analgesic effect of intradermal sterile water block for back pain during labor	Active labor; back pain	RCT, Study group (n = 141) 4 x 0.1 mL sterile water IC; Control group (n = 131) 4 x 0.1 mL NaCl IC; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	Significantly greater reduction of VAS score in the sterile water group compared with the NaCl group, up to 90 min after treatment
Ader et al. (1990)^[9]	Investigate the efficacy of sterile water papules for back pain during labor	Pregnant (wk ≥ 37); first stage of labor; back pain; pain relief required	RCT, Study group (n = 24) 4 x 0.1 mL sterile water IC; control group (n = 21) 4 x 0.1 mL NaCl SC; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	Significantly increased reduction of VAS score in the sterile water group compared with the NaCl group; analgesic effect up to 90 min
Lytzen et al. (1989)^[13]	Evaluate if sterile water papules can be an alternative for alleviating back pain	Established labor	Study group (n = 83) 4 x 0.1 mL sterile water IC; lumbosacral injection were given	VAS; ungraded 0 = no pain, 10 = unbearable pain	VAS score reduced significantly 3 hours after injection compared with just before administration
Trolle et al. (1986)^[16]	Evaluate if back pain during labor can be treated with IC sterile water papules	Primipara; pregnancy (wk ≥ 37); cervix dilatation ≤4 cm	RCT, Study group (n = 38) 4 x 0.1 mL sterile water IC; Control group (n = 38) no treatment; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	The treatment group experienced significantly better pain relief compared with the control group, up to 60 min after treatment

IC = intracutaneous; ID = intradermal; NaCl = sodium chloride; RCT = randomized controlled trial; SC = subcutaneous; TENS = transcutaneous electrical nerve stimulation; VAS = visual analog scale.

Table 2. Demographic Data for the Study Participants (N = 132)
Demographic Characteristic	n (%)*
Years of age, mean (± SD)	49(8)
Years of experience mean (± SD)	14(9)
Number of births attended per year mean (± SD)	88(8)
Practice setting for births^†
Hospital	107(95)
Birth center	13(10)
Home birth	3(3)
Work Status
Working full-time	93(70)
Working part-time	20(15)
Retired	7(5)
Not attending births	12(9)

SD = standard deviation.
*Data reported as n (%) unless otherwise noted.
^†Some midwives reported that they practice in more than one setting.

Table 3. Number of Participants Reporting Different Kinds of Pain Relief Methods for Labor Pain and the Estimated Frequency of Use in Clinical Practice (N = 107)
Methods	Number of Midwives Reporting Use n (%)	Mean (Range)	± SD
IM or IV analgesia	102(95)	27(0-98)	20
Traditional epidural analgesia	82(77)	38(0-95)	27
Sterile water injections	34(32)	1.5(0-30)	4
"Walking" epidural analgesia	28(26)	10(0-80)	22
Other	26(24)	8(10-90)	22
Hydrotherapy	20(19)	38(10-90)	22
Acupressure	19(18)	2.6(0-15)	8
Acupuncture	4(0.04)	0.3(0-15)	1.8
Paracervical nerve block	1(0.01)	0.2(0-10)	1.2

IM = intramuscular; IV = intravenous; SD = standard deviation.

Table 4. Reasons Stated for Not Using Sterile Water Injections Technique for Pain Relief (N = 143)*
Reasons	n (%)
No experience using sterile water injections	60(46)
No training using sterile water injections	46(35)
Resistance to use or not allowed in setting	17(13)
Do not feel comfortable using them	10(8)
Other	7(5)
Do not like them	2(2)
Nurses not allowed to help	1(1)

Some participants gave more than one answer.
*Seventy-three participants did not use sterile water injections.

Table 1. Summary of Studies of Sterile Water Injections as Relief for Labor Pain
Study (Year)	Objective	Inclusion Criteria	Design	Instrument	Results
Bahasadri et al. (2006)^[10]	To evaluate the efficacy of SC sterile water injection in reduction of labor pain compared with placebo	First stage of labor; planned normal vaginal delivery	RCT, Intervention group (n = 50) 1 x 0.5 mL sterile water injection SC; Control group (n = 50) 1 x 0.5 mL saline SC	Face rating scale	The median pain score in the sterile water group was significantly lower than the placebo group at 10 min, as well as 45 min, after the injection
Wiruchpongsanon (2006)^[17]	To study the effectiveness of IC injection of sterile water in relieving low back pain during labor in Thai women	Pregnant women (wks 37-42); active first stage of labor; low back pain	RCT, Treatment group (n = 25) 4 x 0.1 mL sterile water IC; Placebo group (n = 25) 0.1 mL saline IC	VAS	Mean pain reduction was significantly greater in the treatment group compared to the placebo group at 30 min, 1 and 2 hours after injection (P < .001)
Märtensson et al. (2000)^[3]	To investigate whether, during injections of sterile water, there is any difference in perceived pain between IC and SC injections	Women aged 18-45 years; not pregnant; no pain conditions experienced during the trial	RCT, Cross-over design: group 1 (n = 50); group 2 (n = 50); all women were given both IC and SC injections in randomized order	VAS	IC injections of sterile water showed to be significantly more painful than SC injections even when trial, day and injection location were taken into consideration (P < .001)
Märtensson and Wallin (1999)^[14]	To evaluate relief of pain in labor with SC and intracutaneous injections of sterile water vs placebo	Pregnant women (wks 37-42); first stage of labor; severe lower back pain	RCT, Treatment group 1 (n = 33) 4 x 0.1 mL sterile water IC; Treatment group 2 (n = 33) 4 x 0.5 mL sterile water SC; Placebo group (n = 33) 4 x 0.1 mL saline SC	VAS	The pain reduction was significantly greater in both treatment groups compared to placebo at 10 and 45 min after treatment
Labrecque et al. (1999)^[12]	To compare sterile water injections and TENS for low back pain during labor	Pregnancy (wk > 36); low-risk; active first stage of labor; low back pain	RCT, Group 1 (n = 11) 4 x 0.1 mL sterile water IC; Group 2 (n = 12) TENS; Group 3 (n = 12) standard care (bath, massage, mobilization)	VAS	Sterile water injections are more effective than standard care and TENS for low back pain
Dahl and Aarnes (1991)^[11]	To reevaluate the method and factors possibly influencing its efficacy	Healthy women; pregnant (wks 38-42); single gestation	Group 1 (n = 101) 2-4 injections of sterile water IC; group 2 (n = 50) dry needle injections; group 3 control group (n = 117) conventional treatment; lumbosacral and/or suprapubic injections used	VAS ungraded 0 = no pain, 10 = unbearable pain	Sterile water papules provided better relief for labor pain in the IC group compared with the dry needle group; early treatment yielded best effect
Trolle et al. (1991)^[15]	Evaluate the analgesic effect of intradermal sterile water block for back pain during labor	Active labor; back pain	RCT, Study group (n = 141) 4 x 0.1 mL sterile water IC; Control group (n = 131) 4 x 0.1 mL NaCl IC; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	Significantly greater reduction of VAS score in the sterile water group compared with the NaCl group, up to 90 min after treatment
Ader et al. (1990)^[9]	Investigate the efficacy of sterile water papules for back pain during labor	Pregnant (wk ≥ 37); first stage of labor; back pain; pain relief required	RCT, Study group (n = 24) 4 x 0.1 mL sterile water IC; control group (n = 21) 4 x 0.1 mL NaCl SC; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	Significantly increased reduction of VAS score in the sterile water group compared with the NaCl group; analgesic effect up to 90 min
Lytzen et al. (1989)^[13]	Evaluate if sterile water papules can be an alternative for alleviating back pain	Established labor	Study group (n = 83) 4 x 0.1 mL sterile water IC; lumbosacral injection were given	VAS; ungraded 0 = no pain, 10 = unbearable pain	VAS score reduced significantly 3 hours after injection compared with just before administration
Trolle et al. (1986)^[16]	Evaluate if back pain during labor can be treated with IC sterile water papules	Primipara; pregnancy (wk ≥ 37); cervix dilatation ≤4 cm	RCT, Study group (n = 38) 4 x 0.1 mL sterile water IC; Control group (n = 38) no treatment; lumbosacral injections were given	VAS ungraded 0 = no pain, 10 = unbearable pain	The treatment group experienced significantly better pain relief compared with the control group, up to 60 min after treatment

IC = intracutaneous; ID = intradermal; NaCl = sodium chloride; RCT = randomized controlled trial; SC = subcutaneous; TENS = transcutaneous electrical nerve stimulation; VAS = visual analog scale.

Appendix: Sample Procedural Guidelines for Sterile Water Injections

Purpose: To relieve lower back pain during labor

Contraindication: Patient declines procedure

Procedure:

Obtain order from midwife or physician.
Explain procedure to the woman using the diagram to describe area of injection. Be sure that the woman understands that an intense burning sensation will accompany the injection, but that back pain relief will occur within 1 to 3 minutes and will last from 1 to 2 hours. Obtain verbal consent and document in progress note.
Assemble equipment: two 2-mL syringes with 25 gauge needles, preservative-free sterile water (do not use 0.9% saline), and alcohol swabs.
Position woman either sitting, upright, or laterally. Have labor partner or another staff member hold woman's hand and offer support and encouragement during the procedure.
Identify four areas for injection sites (Figure 1).* Some people like to mark the areas to be injected with a pen. The sacral dimples can be palpated for guidelines. In Sweden, midwives often give the injections where the mother feels the pain in her back. Ask the woman to point out the area for pain location in the lumbosacral region.
Draw up 1.0 mL of sterile water in each of two syringes. It is possible to use one syringe twice.
Cleanse the skin with an alcohol swab.
Plan to do the injections during a contraction (preferred) or between contractions (if woman's preference). Plan for two people (preferred) so that injections can be done simultaneously on each side to minimize the time and pain of injections. They can all be done by one person if necessary. Rapidly inject 0.5 mL of sterile water subcutaneously^† in the chosen areas. Avoid touching or rubbing this area after injections.
The procedure can be repeated once the pain relief wears off.
One can document the pain scores before and after the injections. Also, results should be recorded in the progress notes.

*Of 10 studies, six were done giving the injections in Michaelis' rhomboid, and four at painful points in the lumbosacral area. Both sites gave good pain relief.

^†Because of the results from some studies showing reduced injection pain and good pain relief from subcutaneous injections, the authors recommend the subcutaneous injection technique. However, intracutaneous injections can be used if one prefers.

Comments

Commenting is limited to medical professionals. To comment please Log-in.

Comments on Medscape are moderated and should be professional in tone and on topic. You must declare any conflicts of interest related to your comments and responses. Please see our Commenting Guide for further information. We reserve the right to remove posts at our sole discretion.