The Silent Guardian: How Transvaginal Sonography Saves High-Risk Pregnancies from Preterm Labor

A 31-year-old woman visited Wockhardt Hospitals, Mumbai Central presented with primary infertility of seven years due to polycystic ovaries and her husband’s oligoasthenozoospermia (OATS). Under Dr Rana Choudhary, Consultant Obstetrician, Gynecologist & Fertility Specialist, the patient conceived via in-vitro fertilization (IVF), and all embryos were frozen. In a subsequent cycle, she underwent frozen embryo transfer (FET) and conceived a singleton. Her antenatal course was uneventful, but at 26 weeks, she reported heaviness and discomfort in the lower abdomen and vulva. Examination revealed a 26-week-sized uterus with no uterine contractions and a fetal heart rate of 140 beats per minute. A transvaginal sonography (TVS) revealed a short cervix (2.3 cm) with a closed internal Os.

Given her symptoms, she was started on vaginal progesterone suppositories and advised bed rest. A repeat TVS after 10 days showed no change in cervical length. Monitoring continued biweekly, and at 30.2 weeks, her cervical length reduced to 1.32 cm. She was admitted, and given head-low bed positioning, complete bed rest, intravenous antibiotics, and oral probiotics. An emergency cervical cerclage was performed under spinal anesthesia using the modified Shirodkar technique. Post-surgery, she was discharged after two days with a recommendation for rest.

Subsequent sonography showed maintained cervical length with the cerclage in place. At around 35-36 weeks, cervical funnelling was observed. The cerclage stitch was removed at 37 weeks, leading to spontaneous labor and the delivery of a healthy male baby with an Appearance, Pulse, Grimace, Activity and Respiration (APGAR) score of 9/10. The postpartum period was uneventful.

Cervical incompetence, a leading cause of late miscarriages and preterm labor, is often diagnosed retrospectively after multiple poor obstetric outcomes. Symptoms may include mild abdominal cramping, backache, pelvic pressure, or vaginal discharge. High-risk women, particularly those with prior second-trimester losses or cervical surgeries, benefit from routine TVS for early diagnosis and management.

Previously, cervical incompetence was assessed through methods like hysterosalpingography and dilator assessments, which are now obsolete. Today, TVS is the gold standard for diagnosing cervical incompetence. A cervical length of 25mm or less on TVS, with or without funneling, indicates incompetence. Immediate management can prevent preterm delivery and improve neonatal outcomes.

Conservative methods like bed rest and progesterone supplementation have limited efficacy. Surgical interventions, such as McDonald’s and modified Shirodkar cerclage, are more effective. McDonald cerclage involves placing multiple sutures high in the cervix, while Shirodkar cerclage places the stitch close to the internal os after mucosal dissection. In emergencies, Trendelenburg positioning and a Foley catheter may help. Transabdominal cerclage is reserved for severe cases with prior failures, requiring laparotomy for suture removal or fetal delivery.

Early identification and management of cervical incompetence, particularly in high-risk women, are crucial. Routine TVS during anomaly scans and attention to symptoms like lower abdominal heaviness and vaginal discharge can prevent preterm deliveries and improve neonatal morbidity and mortality.