Patricia A. Pastore, MSN, RN, FNP; Dianne M. Loomis, MSN, RN-CS, FNP; John Sauret, MD, FAAFP

Disclosures

J Am Board Fam Med. 2006;19(6):621-626. 

In This Article

Methods

Electronic review of the literature from 1975 to 2005 using MEDLINE, CINAHL, and Cochrane Controlled Trials Register databases was conducted by two family nurse practitioners and a family physician using the key words "appendicitis" and "pregnancy." Studies included in this review were English-language and applicable to US clinical practice. No articles were found that focused specifically on appendicitis in pregnancy in the primary care setting. The bibliographies of all included articles were reviewed and selected for inclusion. These case studies were approved by the Health Sciences Institutional Review Board of the State University of New York at Buffalo.

Epidemiology

Although a rare presentation, appendicitis is one of the most common causes of an acute abdomen in pregnancy, occurring in approximately 1 in 1500 pregnancies.[1,2] This represents an overall incidence of 0.05% to 0.07% and does not appear to be any difference in the nongravid population.[3,4] One report of a reduced incidence of appendicitis during pregnancy suggested a possible protective effect, and the mean age is 28 years.[5]

Incidence rates in the first trimester range from 19% to as high as 36%.[2,3,6,7] There is a higher incidence of appendicitis in the second trimester, ranging from 27% to 60%.[2,3,6] Although incidence decreases from 15% to 33% in the third trimester; some studies reported a 59% incidence in the third trimester.[2,3,6,7] Perforation rates for pregnant patients have been reported as high as 55% of cases, compared with 4% to 19% of the general population.[3,8,9]

Due to the lack of specificity of the preoperative evaluation; the pathologic diagnosis of appendicitis is confirmed in only 30% to 50% of cases.[2,6,7] The first trimester yields a greater accuracy, but more than 40% of patients in the second and third trimester will have a normal appendix.[10] Overall, normal histology was reported to be 11% to 50%.[11,12] Appendicitis was correctly diagnosed 50% to 86% of the time.[3,6,7,11] The risk of delay in diagnosis is associated with a greater risk of complications such as perforation, infection, preterm labor, and risks of fetal or maternal loss.[6,8] Maternal mortality has been reported from none to 2%.[2,3,6,7] An unruptured appendix carries a fetal loss of 1.5% to 9%, while this rate increases up to 36% with perforation.[2,6,13]

The risk of perforation increases with gestational age, and perforation in the third trimester often results in preterm labor.[3] Delay in surgical intervention carries increased fetal loss.[14] The risk for premature delivery is the greatest during the first week after surgery. However, maternal mortality is very low.[2,6,7] This may be due to rapid administration of antibiotics, close perioperative monitoring, improved cooperation between general surgeons, obstetricians, and anesthesiologists and improved perioperative care.

Diagnosis

The most common presenting symptoms include anorexia, nausea, vomiting, and right lower quadrant pain.[2,8,15] Fever and tachycardia may not be present during pregnancy.[8,15] Right upper quadrant pain, uterine contractions, dysuria, and diarrhea can also be present.[1,3,6] It is believed that the appendix changes its location during pregnancy with an upward displacement toward the costal margin in the later stages of pregnancy (Figure 1).[16,17] Patients may then present with right upper quadrant pain or entire right-sided pain, although the relocation of the appendix during the later stages of pregnancy and right upper quadrant pain was not reproduced in some patients.[1] A presentation with right upper quadrant pain can be highly variable with an incidence as high as 55%.[3]

Figure 1.

Changes in position of the appendix as pregnancy advances (MO, month, PP, postpartum). As modified from Baer and associates. With permission from The McGraw-Hill Companies.

It is important to note that there is no one reliable sign or symptom that can aid in the diagnosis of appendicitis in pregnancy, and the classic signs of appendicitis such as positive Rovsing's and psoas sign have not been shown to be of any clinical significance in diagnosing an acute appendicitis in pregnancy.[6] Rectal pain and vaginal tenderness especially in the first trimester may be evident.

Differential Diagnosis

Both obstetrical and gynecological conditions can present with abdominal pain and mimic appendicitis[6,8,15] ( Table 1 ). A thorough history and a careful physical examination should lead the evaluating clinician to formulate a differential diagnosis that is appropriate for the individual. Nonobstetrical/nongynecological conditions include gastroenteritis, urinary tract infections, pyleonephritis, cholecystitis, cholelithiasis, pancreatitis, nephrolithiasis, hernia, bowel obstruction, carcinoma of the large bowel, mesenteric adenitis, and rectus hematoma, pulmonary embolism, right-lower-lobe pneumonia, and sickle cell disease.[18,19] Gynecologic and obstetric conditions include ovarian cyst, adnexal torsion, salpingitis, abruptio placenta, chorioamnionitis, degenerative fibroid, ectopic pregnancy, preeclampsia, round ligament syndrome, and preterm labor.[18,19] One study demonstrated that appendicitis occurred in approximately half of their sample; ovarian cysts, mesenteric adenitis, fibromyoma uteri, varicose veins in the parametria, ileus, salpingitis, and torsion were the other pathologies identified.[2]

Diagnostic Testing

Accurately identifying acute appendicitis in pregnancy can be a diagnostic dilemma. The reluctance to operate in pregnancy adds to delays, yet diagnostic imaging techniques have shown promise in facilitating and supporting the diagnosis. Graded compression ultrasound has shown to be highly sensitive and specific although to a lesser degree after a gestational age of 35 weeks due to technical difficulties. This noninvasive procedure should be considered first in working up suspected acute appendicitis.[20] Although considerations regarding operator technique, large body habitus and possible obscuring bowel and gas may not allow for a conclusive preoperative diagnosis.[21]

Selective imaging of the appendix using Helical Computed Tomography has recently shown to be a safe and potentially reliable tool to accurately identify appendiceal changes in appendicitis. Radiation exposure using this test is 300 mrad, which is below an accepted safe level of radiation exposure in pregnancy of 5 rad. Reliance on radiographic studies may not be cost-effective, and may deter from careful and timely serial physical exams.[22]

Chest radiograph may be useful in identifying right lower lobe pneumonia from appendicitis in pregnant patients with right-sided abdominal pain. A plain abdominal radiograph can be used to identify air fluid levels or free air but offers little diagnostic value. Radiation exposure to the fetus is less than 300 mrad.

Laboratory evaluation may not be helpful and cannot be relied on.[11] Leukocytosis in pregnancy can be as high as 16,000 cells/mL with bandemia present and still considered a normal variant and not a clear indicator of appendicitis. During labor, it may rise to 30,000 cells/mL, and not all pregnant patients with appendicitis have leukocytosis. It is not a reliable marker, as up to 33% of cases may have a leukocyte count greater than 15,000/mm[4,8]

Management and Treatment

Early surgical intervention, with less than a 24-hour delay, has shown to be vital in minimizing both maternal and fetal morbidity and mortality. Surgical delays of more than 24 hours from the time of presentation have been associated with appendiceal perforation and significant fetal loss and cases of maternal mortality.[8,14] Various tocolytic agents are used prophylactically for uterine irritability; however their efficacy has not been demonstrated.[2,6]

Antibiotic use during or after surgery may expose the developing fetus to potentially teratogenic substances.[10] Pregnancy related pharmacodynamic changes result in reduced maternal plasma levels of antibiotics.[23] Gentamycin and related aminoglycosides have been associated with nephrotoxicity and ototoxicity, while tetracyclines may cause permanent tooth discoloration and long bone malformation. Fluoroquinolones may cause dysplasia of cartilage and arthropathies in children so are not currently recommended in pregnancy. If perforation, peritonitis, or gangrenous appendix has occurred, broad-spectrum antibiotics with anaerobic coverage such as the second-generation cephalosporins would be appropriate.[12] Perioperative (prophylactic) antibiotics were administered to 94% of the patients undergoing appendectomies of which 60% were second-generation cephalosporins.[9] Ampicillin or cephalosporins are used in combination with metronidazole in cases with perforated or gangrenous appendix.[6]

Laparotomy versus Laparoscopic Surgery

Assessment for open laparotomy is dependent on gestational age since the appendix progressively relocates. This is typically from McBurney's point, and then rising above the iliac crest at about midgestation, then upward to the gallbladder.[16] McBurney's point is the point situated about one-third the distance between the right anterior-superior iliac spine and the umbilicus. This area provides effective access for appendectomy throughout pregnancy, even in the third trimester.[24]

Pregnancy is not considered to be a contraindication for laparoscopic approach to appendectomy.[25] Fetal health complicates the management of the gravida patient with acute abdominal pain. When appendicitis is suspected, timely obstetric as well as a general surgical consult is necessary. Laparoscopic surgery in the pregnant patient has not been broadly accepted in the latter second and third trimester due to the concern regarding fetal wastage, the effects of carbon dioxide on the developing fetus and the long-term effects of this exposure.[26] Laparoscopy procedures take approximately 50% longer with conflicting studies showing decreased length of stay and hospitalization.[9,27] Questions arise regarding the risk for decreased uterine blood flow due to increased intraabdominal pressures from insufflation and the possibility of fetal carbon dioxide absorption.[28] Use of nitrous oxide pneumoperitoneum has been advocated[25] although technical difficulties arise with the gravid uterus. Blind placement of the Veress needle, or primary port, has resulted in puncturing and subsequent pneumoamnion.[27,29]

With improved technique, laparoscopy surgery has been shown to offer some advantages over open laparatomy: decreased postoperative pain, reduced hospital, and wound morbidity.[29] Postoperatively, early mobilization is advantageous for prevention of thromboembolism as occurrence rates of deep vein thrombosis are higher in pregnancy. Early mobilization also reduces the occurrence of incision scars, hernias, and decreases fetal depression secondary to pain and narcotic use.[30]

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