Why does ectopic pregnancy cause severe abdominal pain in pregnancy?

An ectopic pregnancy grows outside the uterine cavity, commonly in a fallopian tube. As it enlarges, the tube and nearby tissue are stretched in a confined space. This can produce intense pain in the lower abdomen or on one side. A tear can release blood into the abdomen, irritating the lining and causing pain that becomes sudden, widespread, or associated with shoulder-tip discomfort. Blood loss can also lead to weakness, dizziness, or fainting.

Severe Abdominal Pain in Pregnancy is a common presentation of Ectopic Pregnancy. Severe pain in pregnancy has other possible causes too, but it should be treated as a warning symptom until assessed.

If you are pregnant or pregnancy is possible and the pain is severe, seek emergency medical help now. Do not drive yourself if you feel dizzy or weak. Tell emergency staff about any vaginal bleeding, the side and onset of pain, your pregnancy dates if known, and previous ectopic pregnancy or fallopian-tube problems. Assessment may include monitoring, blood tests, examination, and ultrasound.

Call emergency services for sudden or worsening pain, fainting, severe dizziness, shoulder-tip pain, heavy vaginal bleeding, confusion, shortness of breath, or a pale and clammy appearance. These symptoms may accompany internal bleeding and need immediate treatment. Stay with someone while help is arranged if possible.

Where is the pregnancy located? Could internal bleeding explain the pain? What treatment options are appropriate, and which symptoms require an immediate return?