If a hernia is present before pregnancy, it will become more prominent as the pregnancy proceeds. Umbilical hernias might present as a “belly button” (umbilical) bulge, or an increased preexisting “outey.” Inguinal bulges may develop in the groin for a few reasons. Some of these bulges are hernias and others are fluid collection. Some are painful. Groin pain can also occur without bulges in the third trimester because of pressure from the enlarging uterus or strain on the round ligaments of the uterus that exit the pelvis through the groin. A sensitive nerve (genital branch of the genitofemoral nerve) accompanies this ligament. The risk of an enlarging hernia is that bowel can become incarcerated or stuck causing severe pain and bowel blockage. Fortunately, this is rare. If the hernia is felt to be dangerous, repair can be done with local anesthesia with open technique. Sometimes a hernia will show up in the second trimester and disappear in the third trimester because the enlarged uterus blocks off the inguinal floor. The clinical preference is to NOT repair hernia during pregnancy unless there is an acute event or imminent risk. Laparoscopy is usually undesirable during pregnancy except for unavoidable inflammatory indications intraabdominal processes like appendicitis or gallbladder requirements. Many bulges subside after delivery and are difficult to detect as the abdominal wall and inguinal area recoil to normal dimensions and tone. The defect in the abdominal wall might diminish enough to be undetectable and pain frequently resolves. Postpartum repair is advisable when the bulge persists or future pregnancies are planned. Otherwise, a “wait and see” posture may be taken.
The abdominal midline can be disrupted by large pregnancies and followed by large midline bulges (diastases) or hernias. The spread of midline muscle (diastasis) in general is not an indication for surgery and not reimbursable by insurance companies, unless it progresses to a hernia. Cosmetic consideration might still make repair desirable. Progression of the bulge and thinning of the tissue reflecting off the separation can result in a ventral hernia with bowel progressively protruding into a sac above the abdominal wall. The disruption of residual retaining structure can be painful as can be the protruding intestine which has some risk of complications.
C-Sections are performed for various reasons. Some authors have described a ”Post-Pfannensteil syndrome” to describe persistent symptoms. The Bikini incision (Pfannensteil) provides a desirable cosmetic scar. Access is done under the skin incision through a parallel transverse incision in the fascia (or covering of the midline muscles) but the muscles are then spread apart vertically up to the umbilicus perpendicular to the low skin incision. The older option was a vertical incision. This incision was not originally designed by Pfannensteil (1900) for the delivery of babies. If the baby is too large to be delivered through the space created by this incision by retracting the rectus abdominus muscle layer, access must be extended laterally by dissection into the medial groin area or the muscle must be vigorously retracted widely to both sides. An older technique called the Maylard Incision transects the rectus muscle to make more space. This might impact future function. Extremely wide exposure requires penetration and/or incision of the more lateral oblique muscle layers and can impact blood and nerve supply to these muscles and the rectus abdominus muscle. Numbness and/or neuralgia, persistent pain, might follow nerve compromise.
If this access is required urgently or emergently, local structures present greater obstacles. Even wider exposure might require a Cherney incision or extension further laterally. All of these extensions create more tissue compromise than a straight forward Pfannensteil, yet leave a variation of a Bikini scar.
All of these extensions are essentially obligatory at the time of delivery to accomplish the prompt and atraumatic delivery of a healthy baby. After extraction of the baby which receives much operating room attention, the incision must be precisely closed restoring the anatomy and function of individual myofascial layers.
Healing of the layers of the wound depends on many factors. The reported incidence of hernias in these wounds is remarkably low. Long term incidence is difficult to actually ascertain since hernias and pain can occur for years after patients stop visiting monitoring obstetricians and probably do not get reported by PCPs. Hernias can slowly develop between muscle and not penetrate the overlying fascia of the muscle and present later as a bulge or hernia.
The emergency incision might impact local nerves and muscle structure during delivery or during wound healing. With multiple pregnancies, bulges and hernias can sequentially enlarge.
A repeat C-section must be done through scar and less well-defined tissue layer and can make identification of structures difficult. Nerves already involved and fixed in scar might be more easily stressed with retraction.
For example: A 40-year old woman, 5’3” and previously 115#, delivered first of three babies, gained 40# and noted a bulge between her midline muscle. Two years later, she had twins delivered by an urgent C-Section. Abdominal skin developed stretch marks and became redundant. The midline bulge increased near the navel where she noted a hernia and left groin pain under the edge of the extended scar. Two years later she had another large baby delivered by elective C-section and subsequently noted marked midline bulging and poor abdominal tone. Bowel was felt in the midline hernia. Her surgeon and a plastic surgeon teamed up to do a ventral hernia repair reinforced with mesh and an abdominoplasty with neurolysis. She benefited from the cosmetic and functional result.
Supra pubic incisions can result in hernia that can be repaired with either open or laparoscopic technique. The suprapubic aspect of these repairs presents the greatest risk for recurrence because mesh, when used, must be anchored on pelvic structures. If mesh is not used, recurrence rates are higher.
A significant percentage of women have pain related to the Bikini incision. This is usually laterally and related to inguinal nerve entrapment related to the scar of the extended incision. The pain might be delayed until the time when mom needs to be chasing toddlers. Other reasons for pain in these incisions, like hernia formation, must also be considered. Skin pain can be related to keloid and suture granulosa. A painful solid mass might be caused by implantation of endometriosis or an unusual myofascial proliferative disorder, fibromatosis. Gynecologic reasons for the pain must be ruled out.
The diagnosis and decision to intervene is difficult and best made by the abdominal hernia surgeon to whom the Obstetrician refers the patient for consultation. It is important that the abdominal surgeon is familiar and experienced with these obstetrical and Gynecology entities, the expectation of postpartum persistence or resolution of symptoms and findings and options for timing and methods of treatment. Repair of hernias, excision of masses and attention to nerve entrapment are, of course, best managed at the primary intervention. In young women, repair must consider resultant durability during future pregnancies and repeated access during future C-section.