Ectopic Pregnancy

Definition/diagnostic criteria Ectopic pregnancy occurs when a fertilised egg implants outside the uterine cavity, most commonly in the fallopian tubes. The diagnosis is supported by ultrasound and serum human chorionic gonadotrophin (hCG) levels.

Epidemiology In the UK, ectopic pregnancies account for approximately 1% of all pregnancies. The incidence is influenced by factors such as previous ectopic pregnancies, pelvic inflammatory disease, tubal surgery and assisted reproductive technologies.

Diagnosis Diagnosis of ectopic pregnancy is multifactorial, involving clinical features, investigations, and diagnostic imaging.

Clinical features: Symptoms typically include unilateral pelvic pain and vaginal bleeding in early pregnancy. However, presentation can vary from asymptomatic to acute abdominal pain indicative of a ruptured ectopic pregnancy. Shoulder tip pain can occur due to diaphragmatic irritation by blood in the peritoneal cavity.

Investigations Initial assessment includes a pregnancy test to confirm pregnancy. Transvaginal ultrasound is the primary imaging modality, aiming to locate the pregnancy. However, an ectopic pregnancy may not always be visible on ultrasound. In such cases, the concept of a ‘pregnancy of unknown location’ (PUL) is used.

Serial measurements of serum hCG are crucial. In a healthy intrauterine pregnancy, hCG levels typically double every 48 hours. Slower increases, plateauing or decreasing levels suggest a non-viable intrauterine pregnancy or an ectopic pregnancy. Progesterone levels can also aid diagnosis, with low levels (<20 nanomoles/L) being suggestive of an ectopic pregnancy or miscarriage.

Treatment Treatment options for ectopic pregnancy include expectant management, medical treatment or surgery. The choice depends on the clinical presentation, the size and location of the ectopic pregnancy, and the patient’s preference.

• Medical treatment: Methotrexate, an antimetabolite, is used in cases where the ectopic pregnancy is unruptured and less than 35mm without a visible heartbeat. It is contraindicated in liver disease, renal impairment, blood dyscrasias and peptic ulcers.
• Surgical treatment: Laparoscopic surgery is the preferred method for treating ectopic pregnancies that are not suitable for medical management. Salpingectomy (removal of the affected fallopian tube) or salpingostomy (removal of the ectopic pregnancy while preserving the tube) are common procedures.

Prognosis The prognosis following an ectopic pregnancy varies. Early detection and treatment have significantly reduced associated mortality. However, fertility may be affected, particularly if the fallopian tubes are damaged. The risk of recurrent ectopic pregnancy is increased, estimated at around 10%.