A hernia occurs when an organ or tissue pushes through a weak spot in the muscle or connective tissue, creating a visible bulge in the abdominal wall. The physiological changes of gestation significantly increase the risk of a hernia and often reveal a pre-existing weakness. This article explores the specific mechanisms, the types most often encountered, and the necessary steps for diagnosis and management during this time.
Physiological Reasons Why Pregnancy Increases Risk
The primary mechanical factor contributing to hernia risk during pregnancy is the progressive increase in intra-abdominal pressure. As the uterus expands to accommodate the growing fetus, it exerts a constant force against the abdominal wall. This prolonged pressure strains the fascia, the strong, fibrous layer of tissue that holds the abdominal contents in place.
Simultaneously, hormonal shifts play a large role in weakening the body’s connective tissues. Hormones such as relaxin soften ligaments and joints in preparation for childbirth, which also affects the abdominal fascia and muscle attachments. This softening, combined with the stretching of the abdominal muscles, creates a less resilient abdominal wall, making it easier for internal tissues to push through weak points.
This environment of high pressure and weakened tissue is why a hernia may develop for the first time or become symptomatic during pregnancy. The strain from common activities like coughing, vomiting due to morning sickness, or straining during bowel movements further compounds the stress on the weakened abdominal wall.
Types of Hernias Common During Pregnancy
The most frequently observed type of hernia during pregnancy is the umbilical hernia, appearing as a soft bulge directly at or near the navel. This occurs because the area around the belly button is a naturally weak point where the umbilical cord once passed. The intense internal pressure from the gravid uterus pushes fatty tissue or intestine through this opening.
Another common type is the hiatal hernia, where a portion of the stomach pushes upward through the opening in the diaphragm, the muscle separating the chest and abdomen. The growing uterus exacerbates this by pushing abdominal organs upward, forcing the stomach through the esophageal hiatus. Symptoms typically involve heartburn, chest pain, or difficulty swallowing.
Less common are inguinal and femoral hernias, which present as bulges in the groin or upper thigh. Inguinal hernias occur in the inner groin, while femoral hernias are just below the inguinal crease. Lastly, an incisional hernia can develop at the site of a previous surgical scar, such as from a prior Cesarean section, as the scar tissue represents a weakened area.
Identifying Symptoms and Recognizing Emergencies
The initial sign of a hernia is usually a visible bulge or lump in the abdomen or groin that is often more noticeable when standing or straining. This bulge may disappear when lying down or when gentle pressure is applied, indicating a reducible hernia. Accompanying this protrusion is often a localized dull ache, pressure, or a feeling of heaviness that intensifies with movement, coughing, or bending over.
It is important to differentiate these common symptoms from a medical emergency, which can occur if the hernia becomes incarcerated or strangulated. Incarceration means the tissue is trapped outside the abdominal wall and cannot be pushed back in. Strangulation is a dangerous progression where the blood supply to the trapped tissue is cut off, leading to tissue death and requiring immediate intervention.
Signs of strangulation include sudden, severe pain that is disproportionate to the bulge size, along with symptoms of bowel obstruction. These include persistent nausea, repeated vomiting, fever, and an inability to pass gas or have a bowel movement. If the skin over the bulge appears red, purple, or dark, it signifies a lack of blood flow and requires urgent emergency medical care.
Management Options and Surgical Timing
For most asymptomatic or mildly symptomatic hernias discovered during pregnancy, the standard medical approach is conservative management and watchful waiting. This involves monitoring the hernia closely and using non-surgical methods to manage discomfort. Support garments, such as an abdominal binder, can help hold the hernia in place and alleviate pressure.
For hiatal hernias, management focuses on dietary changes and medications to control acid reflux. Strategies to minimize straining, such as treating chronic constipation or coughing, are recommended to prevent the hernia from enlarging. Unless complications arise, surgery is almost always delayed until after delivery.
If the hernia becomes strangulated or causes intolerable pain, emergency surgery is necessary, with the second trimester being the preferred and safest time for the procedure. Elective repair is typically scheduled for several months postpartum, allowing the abdominal wall to recover and hormones to stabilize. In some cases, a small hernia may be repaired simultaneously during a planned Cesarean section.