Stethoscope and Doppler May Outperform Newer Fetal Monitoring Tools

Will Pass

April 16, 2021

For intrapartum fetal surveillance, the old way may be the best way, according to a meta-analysis involving more than 118,000 patients.

Intermittent auscultation with a Pinard stethoscope and handheld Doppler was associated with a significantly lower risk of emergency cesarean deliveries than newer monitoring techniques without jeopardizing maternal or neonatal outcomes, reported lead author Bassel H. Al Wattar, MD, PhD, of University of Warwick, Coventry, England, and University College London Hospitals, and colleagues.

"Over the last 50 years, several newer surveillance methods have been evaluated, with varied uptake in practice," the investigators wrote in the Canadian Medical Association Journal, noting that cardiotocography (CTG) is the most common method for high-risk pregnancies, typically coupled with at least one other modality, such as fetal scalp pH analysis (FBS), fetal pulse oximetry (FPO), or fetal heart electrocardiogram (STAN).

"Despite extensive investment in clinical research, the overall effectiveness of such methods in improving maternal and neonatal outcomes remains debatable as stillbirth rates have plateaued worldwide, while cesarean delivery rates continue to rise," the investigators wrote. Previous meta-analyses have relied upon head-to-head comparisons of monitoring techniques and did not take into account effects on maternal and neonatal outcomes.

To address this knowledge gap, Al Wattar and colleagues conducted the present systematic review and meta-analysis, ultimately including 33 trials with 118,863 women who underwent intrapartum fetal surveillance, dating back to 1976. Ten surveillance types were evaluated, including intermittent auscultation with Pinard stethoscope and handheld Doppler, CTG with or without computer-aided decision models (cCTG), and CTG or cCTG combined with one or two other techniques, such as FBS, FPO, and STAN.

This revealed that intermittent auscultation outperformed all other techniques in terms of emergency cesarean deliveries and emergency cesarean deliveries because of fetal distress.

Specifically, intermittent auscultation significantly reduced risk of emergency cesarean deliveries, compared with CTG (relative risk, 0.83; 95% confidence interval, 0.72-0.97), CTG-FBS (RR, 0.71; 95% CI, 0.63-0.80), CTG-lactate (RR, 0.77; 95% CI, 0.64-0.92), and FPO-CTG-FBS (RR, 0.81; 95% CI, 0.67-0.99). Conversely, compared with IA, STAN-CTG-FBS and cCTG-FBS raised risk of emergency cesarean deliveries by 17% and 21%, respectively.

Compared with other modalities, the superiority of intermittent auscultation was even more pronounced in terms of emergency cesarean deliveries because of fetal distress. Intermittent auscultation reduced risk by 43%, compared with CTG, 66% compared with CTG-FBS, 58%, compared with FPO-CTG, and 17%, compared with FPO-CTG-FBS. Conversely, compared with intermittent auscultation, STAN-CTG and cCTG-FBS increased risk of emergency cesarean deliveries because of fetal distress by 39% and 80%, respectively.

Further analysis showed that all types of surveillance had similar effects on neonatal outcomes, such as admission to neonatal unit and neonatal acidemia. Although a combination of STAN or FPO with CTG-FBS "seemed to improve the likelihood of reducing adverse neonatal outcomes," the investigators noted that these differences were not significant in network meta-analysis.

"New fetal surveillance methods did not improve neonatal outcomes or reduce unnecessary maternal interventions," Al Wattar and colleagues concluded. "Further evidence is needed to evaluate the effects of fetal pulse oximetry and fetal heart electrocardiography in labor."

Courtney Rhoades, DO, MBA, FACOG, medical director of labor and delivery and assistant professor of obstetrics and gynecology at the University of Florida, Jacksonville, suggested that the meta-analysis supports the safety of intermittent auscultation, but the results may not be entirely applicable to real-world practice.

"It is hard, in practice, to draw the same conclusion that they do in the study that the newer methods may cause too many emergency C-sections because our fetal monitoring equipment, methodology for interpretation, ability to do emergency C-sections and maternal risk factors have changed in the last 50 years," Rhoades said. "Continuous fetal monitoring gives more data points during labor, and with more data points, there are more opportunities to interpret and act – either correctly or incorrectly. As they state in the study, the decision to do a C-section is multifactorial."

Rhoades, who recently authored a textbook chapter on intrapartum monitoring and fetal assessment, recommended that intermittent auscultation be reserved for low-risk patients.

"The American College of Obstetricians and Gynecologists has endorsed intermittent auscultation for low-risk pregnancies and this study affirms their support," Rhoades said. "Women with a low-risk pregnancy can benefit from intermittent auscultation because it allows them more autonomy and movement during labor so it should be offered to our low-risk patients."

Al Wattar reported a personal Academic Clinical Lectureship from the U.K. National Health Institute of Research. Khan disclosed funding from the Beatriz Galindo Program Grant given to the University of Granada by the Ministry of Science, Innovation, and Universities of the Spanish Government.

This article originally appeared on, part of the Medscape Professional Network.


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.