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. 2023 Mar;27(6):1-87.
doi: 10.3310/KUYP6832.

Feasibility of a RCT of techniques for managing an impacted fetal head during emergency caesarean section: the MIDAS scoping study

Kate F Walker  1 , Eleanor J Mitchell  2 , Susan Ayers  3 , Nia W Jones  1 , Reuben Ogollah  2 , Natalie Wakefield  2 , Jon Dorling  4 , Phoebe Pallotti  5 , Arani Pillai  6 , Nicola Tempest  7 , Rachel Plachcinski  8 , Lucy Bradshaw  2 , Marian Knight  9 , Jim G Thornton  1
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Feasibility of a RCT of techniques for managing an impacted fetal head during emergency caesarean section: the MIDAS scoping study

Kate F Walker et al. Health Technol Assess. 2023 Mar.

Abstract

Background: Second-stage caesarean sections, of which there are around 34,000 per year in the UK, have greater maternal and perinatal morbidity than those in the first stage. The fetal head is often deeply impacted in the maternal pelvis, and extraction can be difficult. Numerous techniques are reported, but the superiority of one over another is contentious and there is no national guidance.

Objective: To determine the feasibility of a randomised trial of different techniques for managing an impacted fetal head during emergency caesarean.

Design: A scoping study with five work packages: (1) national surveys to determine current practice and acceptability of research in this area, and a qualitative study to determine acceptability to women who have experienced a second-stage caesarean; (2) a national prospective observational study to determine incidence and rate of complications; (3) a Delphi survey and consensus meeting on choice of techniques and outcomes for a trial; (4) the design of a trial; and (5) a national survey and qualitative study to determine acceptability of the proposed trial.

Setting: Secondary care.

Participants: Health-care professionals, pregnant women, women who have had a second-stage caesarean, and parents.

Results: Most (244/279, 87%) health-care professionals believe that a trial in this area would help guide their practice, and 90% (252/279) would be willing to participate in such a trial. Thirty-eight per cent (98/259) of parents reported that they would take part. Women varied in which technique they thought was most acceptable. Our observational study found that impacted head is common (occurring in 16% of second-stage caesareans) and leads to both maternal (41%) and neonatal (3.5%) complications. It is most often treated by an assistant pushing the head up vaginally. We designed a randomised clinical trial comparing the fetal pillow with the vaginal push technique. The vast majority of health-care professionals, 83% of midwives and 88% of obstetricians, would be willing to participate in the trial proposed, and 37% of parents reported that they would take part. Our qualitative study found that most participants thought the trial would be feasible and acceptable.

Limitations: Our survey is subject to the limitation that, although responses refer to contemporaneous real cases, they are self-reported by the surgeon and collected after the event. Willingness to participate in a hypothetical trial may not translate into recruitment to a real trial.

Conclusions: We proposed a trial to compare a new device, the fetal pillow, with a long-established procedure, the vaginal push technique. Such a trial would be widely supported by health-care professionals. We recommend that it be powered to test an effect on important short term maternal and baby outcomes which would require 754 participants per group. Despite the well-known difference between intent and action, this would be feasible within the UK.

Future work: We recommend a randomised controlled trial of two techniques for managing an impacted fetal head with an in-built internal pilot phase and alongside economic and qualitative substudies.

Study registration: This study is registered as Research Registry 4942.

Funding: This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 27, No. 6. See the NIHR Journals Library website for further project information.

Keywords: CESAREAN SECTION; CONSENSUS; FEASIBILITY STUDIES; FETUS; HEAD; HEALTH PERSONNEL; IMPACTED FETAL HEAD; INFANT, NEWBORN; MIDWIFERY; PARENTS; PELVIS; PREGNANCY; PREGNANT WOMEN; PRENATAL CARE; PROSPECTIVE STUDIES; SECONDARY CARE; SELF REPORT; SURGEONS; SURVEYS AND QUESTIONNAIRES.

Plain language summary

Text: One-quarter of UK pregnant women have a caesarean section. Most of these procedures are straightforward, but in a small number of cases unexpected complications can make the birth difficult. One complication, an impacted fetal head, may happen when caesarean sections are done in the second ‘pushing’ stage of labour. If the baby’s head is low and wedged in the woman’s pelvis, lifting it can be difficult, which can result in damage to the mother’s womb and vagina, and to her baby. Occasionally, babies die. There are different techniques doctors and midwives can use to make these births easier, but there is uncertainty around which is best. To plan a trial to test these techniques, we needed to know how often impacted head happens, what techniques are used to manage it and whether or not research is acceptable to parents and health-care professionals. We surveyed doctors and midwives to find out which techniques they use and what training they need. We surveyed parents and pregnant women and interviewed women who had experienced a second-stage caesarean. We collected information from UK hospitals to find out how common this is and the impact on women and babies. We found out the following.

List: • Around 7% of caesareans take place in second stage, and impacted fetal head occurs in 16% of these births.

List: • One-third of women would consent to take part in a trial, if the complication happened to them.

List: • Nearly all midwives and doctors thought that this research was important and would be willing to take part.

Text: Using all of the information we collected, we designed a clinical trial. We wanted to compare two techniques for managing an impacted fetal head. The first is the vaginal push technique, where the doctor or midwife puts their hand into the mother’s vagina to push her baby’s head up, and the second is the fetal pillow, a device inserted into the mother’s vagina before the operation starts to dislodge the baby’s head upwards.

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