Abdominal Pain in Pregnancy – Obstetric & Non-Obstetric Causes

Abdominal discomfort and even mild pain during pregnancy is common and often passed off as a normal part of pregnant state.  However, there are many serious pregnancy-related (obstetric) causes of abdominal pain that may initially start off as discomfort or slight pain and intensify as the condition progresses. There are also non-obstetric causes of abdominal pain which can be very serious in nature. Therefore any intense abdominal pain should not be ignored despite the reassurance that the fetus is not in distress.

In the first trimester, an ectopic pregnancy is one condition that should always be kept in mind. It has to be excluded  in any woman complaining of abdominal pain in early pregnancy because of its potentially dangerous consequences.

Causes of Abdominal Pain in Pregnancy

Abdominal pain in pregnancy may vary from mild to severe. It may be accompanied by other signs and symptoms which will point to a possible cause of the pain. The most important causes of abdominal pain in pregnancy includes :

Ectopic Pregnancy

This is one of the most, if not the most, important cause of abdominal pain in pregnancy because of its very serious implications. Ectopic pregnancy occurs when a fertilized ovum (egg) is implanted in any site other than the uterus. This most commonly occurs in the fallopian tube and such a pregnancy cannot thrive.

An ectopic pregnancy can rupture and become potentially life-threatening. It must be excluded in all cases of abdominal pain in early pregnancy. In fact, ectopic pregnancy must be kept in mind in any woman of child-bearing age with abdominal pain since it may occur even without a woman knowing that she is pregnant.

In early ectopic pregnancy, a history of missed periods indicating pregnancy may be absent  The pain may be accompanied by vaginal bleeding, which can be mistaken for normal periods.  Signs of shock such as faint rapid pulse, hypotension (low blood pressure), and cold clammy skin may be evident.  Weakness, dizziness, and fainting may be associated symptoms.

Spontaneous Abortion (Miscarriage)

Miscarriage or spontaneous abortion is death of a fetus before 20 weeks of pregnancy or weighing less than 500 grams. This may include threatened, inevitable, incomplete, complete, and septic abortion as explained under Types of Abortion. Pain normally subsides once the abortion is complete.

As a rule, vaginal bleeding in the first trimester is the more prominent symptom of a miscarriage.  The pain may be mild to severe, cramping or a dull abdominal pain and there is usually a history of missed periods.  A past history of miscarriage may be reported.

Abruptio Placentae (Accidental Hemorrhage)

This is partial or complete separation of the placenta from the uterus before birth of the baby.  Sudden severe vaginal bleeding may occur although sometimes only slight bleeding may be evident. Sudden intense and unremitting abdominal pain in pregnancy, especially where the uterus feels hard and contracted should raise the concern about abruptio placentae. Signs of fetal distress may also be noted by the physician and the pregnancy is likely to be jeopardized.

Placenta Previa

The placenta is implanted low down in the uterus and  may partially or completely block the cervical os. This can obstruct the descent of the fetus during delivery. The typical symptom is a sudden and severe painless bleed in the third trimester. There may be some initial cramping or even abdominal pain in some of the cases due to the co-existing placental separation (abruptio placentae).

Preterm Labor

Preterm labor is uterine contractions with onset of labor before 37 weeks of pregnancy. Abdominal cramping and pain with low back pain is usually present. It may be accompanied by vaginal discharge and bleeding.

Onset of Normal Labor

Frequent and regular contractions, which increase in duration and intensity is a sign of labor. Intense abdominal pain is noted with each uterine contraction.  A “gush” of water from the vagina or a slow trickle (“water broke”) and “show” or blood stained mucus discharge from the vagina are the typical signs to confirm labor.

Pre-eclampsia

In this condition, there is hypertension (high blood pressure), swelling of the body and protein in the urine (proteinuria) after 20 weeks of pregnancy. In severe cases, abdominal pain, headaches and visual disturbances may occur. Pre-eclampsia can lead to many pregnancy complications affecting both mother and baby.

Rupture of Uterus

This is a rare cause of abdominal pain but is more likely to occur during labor when there is a history of uterine scarring. Apart from abdominal pain, other signs and symptoms include :

  • Signs of shock
  • Vaginal bleeding
  • Signs of fetal distress

Uterine Torsion

In a normal and healthy pregnancy, the uterus rotates 30 to 40 degrees to the right. In rare cases, however, it can cause acute uterine torsion by rotating more than 90 degrees in mid or late pregnancy. Abdominal pain and a hard uterus on examination may be accompanied by shock and urinary retention.

Other Common Causes of Pregnancy Abdominal Pain

Common but less worrying causes of abdominal pain in pregnancy may include :

  • Round ligament pain usually occurs in the second trimester. It is caused by stretching of the round ligament (which helps to support the uterus) in pregnancy. It may be felt as a short jabbing pain in the lower abdomen, usually on changing position or excessive physical activity.
  • Following sexual activity.
  • Gas bloating
  • Abdominal distention
  • Constipation
  • Braxton-Hicks contractions or false labor pains may occur in the second half of pregnancy. These are irregular contractions which do not increase in frequency with increasing intensity. It often resolves upon walking or with a change in position.

Non-Obstetric Causes of Abdominal Pain

Certain conditions causing abdominal pain in the non-pregnant state may also afflict  pregnant woman. These include :

  • Acute appendicitis is not more common in pregnancy but the risk of appendix rupture is increased, most often due to delays in diagnosis and operation. Diagnosis often becomes difficult because the symptoms are not always typical. Although right sided lower abdominal pain is almost always present, it may be misdiagnosed as round ligament pain or a UTI.
  • Urinary tract infection (UTI). Pregnant women are more prone to UTI’s. Lower abdominal pain, frequent urination with a burning sensation, fever, nausea and vomiting may be the symptoms.
  • Gallbladder diseases such as cholecystitis (inflamed gallbladder) and cholelithiasis (gallbladder stones)
  • Acute pancreatitis
  • Peptic ulcer disease
  • Acute intestinal obstruction (refer to Blocked Bowel for information on small intestine obstruction)
  • Kidney stones
  • Gastroenteritis
  • Torsion, hemorrhage or rupture of ovarian cysts
  • Red degeneration or torsion of fibroids
  • Irritable bowel syndrome
  • Inflammatory bowel disease
  • Trauma could be due to accidents, falls, or physical assault. Blunt force trauma or sharp force injuries need to be investigated.
  • Diabetic ketoacidosis

Related Articles

  1. Dizziness in Pregnancy
  2. Vomiting during Pregnancy
  3. Pregnancy Headaches
  4. Pregnancy Fever
  5. Vaginal Bleeding during First Trimester of Pregnancy

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