Ectopic Pregnancy

Ectopic pregnancy affects approximately 1 in 90 pregnancies in the UK. While over 95% occur in the fallopian tube (tubal pregnancy), other rare sites include the cervix, ovary, Caesarean scar, or abdomen. The core issue is that the implantation site cannot accommodate the growing embryo, leading to stretching, pain, and ultimately rupture. Rupture causes massive intraperitoneal haemorrhage, a gynaecological emergency requiring immediate intervention. Key risk factors include previous pelvic inflammatory disease (PID), tubal surgery, previous ectopic pregnancy, IUD use, and assisted reproductive technology (ART/IVF). However, many cases occur without identifiable risk factors. Diagnosis relies on a positive pregnancy test, clinical symptoms, transvaginal ultrasound (TVUS), and serial serum beta-hCG levels. Management strategies range from expectant management to medical (methotrexate) or surgical (laparoscopic salpingectomy), dictated by clinical stability, pregnancy size, and hCG levels. Prompt recognition of a collapsed patient with a positive pregnancy test is paramount for survival.

Ectopic pregnancy results from impaired transport of the blastocyst through the fallopian tube. Damage to tubal cilia (e.g., from Chlamydia infection, smoking) or mechanical obstruction (e.g., adhesions from surgery/endometriosis) prevents the zygote from reaching the uterus. The trophoblastic tissue then invades the tubal wall. Unlike the endometrium, the tubal wall lacks a decidual reaction and cannot support a growing placenta, leading to erosion of blood vessels and eventual rupture of the tube. This causes haemorrhage into the peritoneal cavity, leading to peritonism and hypovolaemic shock. Ectopic pregnancies produce beta-hCG, but often with a slower, sub-optimal rise compared to a healthy intrauterine pregnancy due to poor vascularisation at the implantation site.

Patients typically present between 6-10 weeks gestation. Symptoms include unilateral lower abdominal pain (often constant, cramping), followed by vaginal bleeding (darker, lighter than a normal period). On examination, cervical excitation (pain on moving the cervix) and adnexal tenderness are classic signs. Rupture can cause 'shoulder tip pain' (diaphragmatic irritation from blood) and signs of hypovolaemic shock (tachycardia, hypotension, syncope). In any female of childbearing age presenting with acute abdominal pain or collapse, a pregnancy test is mandatory. Complications are primarily haemorrhage and loss of the fallopian tube, impacting future fertility. Psychological support is crucial for patients experiencing pregnancy loss.

Bedside: Urine pregnancy test (essential and immediate), Vital signs (assess for shock). Bloods: Group and Save (cross-match if unstable), Full Blood Count (Hb for blood loss), serum beta-hCG (serial measurements 48 hours apart to assess rise), Rhesus status. Liver and Renal function are needed if methotrexate is considered. Imaging: Transvaginal Ultrasound (TVUS) is the definitive diagnostic tool. Look for an empty uterus (no intrauterine gestational sac), an adnexal mass ('blob sign', 'bagel sign', or gestational sac with yolk sac/fetal pole) and free fluid in the Pouch of Douglas. If hCG is >1500 IU/L (discriminatory zone) and the uterus is empty, an ectopic pregnancy is highly suspected.

Emergency Management: For suspected ruptured ectopic, follow an ABCDE approach. Secure large-bore IV access, initiate fluid resuscitation, and call for immediate senior surgical and anaesthetic input for urgent laparotomy or laparoscopy. Surgical: Laparoscopic salpingectomy (removal of the affected fallopian tube) is the first-line surgical option for most, especially if the contralateral tube is healthy. Salpingotomy (incision into the tube to remove the pregnancy, preserving the tube) may be considered in specific circumstances (e.g., desire for future fertility, damaged contralateral tube), but carries a higher risk of persistent trophoblast. Medical: Intramuscular Methotrexate is an option for haemodynamically stable patients who are asymptomatic or have minimal pain, with hCG levels typically <1500-3000 IU/L, and no fetal heartbeat on scan. Patients must be compliant with follow-up and use contraception for 3-6 months. Expectant Management: Reserved for highly selected, asymptomatic, stable patients with very low and falling hCG levels, and no adnexal mass on scan. Anti-D Prophylaxis: Essential for all Rhesus-negative women undergoing medical or surgical management of ectopic pregnancy.