Lower segment Caesarean section
A lower segment caesarean section (LSCS), also known as the low transverse cesarean section, is a surgical procedure for delivering a baby through a transverse incision in the lower, thinner segment of the uterus, accessed via a horizontal abdominal incision (laparotomy).[1] This technique, which accounts for approximately 90% of all cesarean deliveries, minimizes blood loss and facilitates easier uterine repair compared to classical vertical incisions.[2] The development of the LSCS marked a significant advancement in obstetric surgery during the early 20th century, when maternal mortality from cesareans exceeded 50% due to infection and hemorrhage risks associated with earlier methods.[3] Pioneered by Scottish obstetrician John Munro Kerr, who introduced the low transverse uterine incision in 1921 and refined it through subsequent publications, the technique built on prior concepts from figures like Ferdinand Adolf Kehrer in 1882 but emphasized the avascular lower uterine segment to reduce complications.[3] By the mid-20th century, it had become the standard approach, dramatically improving outcomes and enabling safer repeat pregnancies. In the procedure, a curved horizontal skin incision (typically Pfannenstiel) is made above the pubic symphysis, followed by layered dissection through the abdominal wall to expose the uterus; a transverse hysterotomy is then performed 2-3 cm below the uterovesical fold, the fetus is delivered, the placenta is removed, and the uterus is closed in one or two layers using absorbable sutures.[1] This method is preferred for its advantages, including lower intraoperative bleeding, reduced adhesion formation, and a decreased risk of uterine rupture in future labors (0.5-1% versus 4-9% for vertical incisions).[2] Indications for LSCS mirror those of cesarean delivery generally and include labor dystocia, fetal distress, breech presentation, placental abnormalities such as previa, and prior cesarean sections where vaginal birth after cesarean is not feasible.[1] While it carries risks like infection (up to 20 times higher than vaginal birth), hemorrhage, and potential injury to the fetus or bladder, its overall safety profile has made it the most performed surgical intervention in obstetrics, with over 1 million procedures annually in the United States alone.[1]Definition and Indications
Definition
The lower segment Caesarean section (LSCS) is the most common form of Caesarean delivery, characterized by a transverse incision made in the lower uterine segment, positioned just above the attachment of the urinary bladder. This technique involves accessing the uterus through an abdominal incision, typically low transverse (Pfannenstiel), followed by the uterine hysterotomy in the lower segment to extract the fetus.[1][4] The lower uterine segment forms during late pregnancy as the isthmus between the uterine corpus and cervix expands and thins, creating a distinct anatomical region that is less vascularized and exhibits reduced contractility compared to the thicker, more contractile upper segment. This segment consists of looser peritoneal attachments and a more passive structure, which facilitates dilation during labor but is well-suited for surgical incision due to its relative avascularity and pliability.[5][4] While the standard incision in the lower segment is transverse (horizontal), vertical variants are occasionally employed in rare circumstances, such as when transverse access is impeded by lateral varicosities or a constriction ring. This approach is favored over classical (upper segment) incisions because it minimizes blood loss, simplifies repair, and supports superior healing outcomes through stable suture placement and efficient scar formation with fewer adhesions.[1][4]Indications
The lower segment Caesarean section (LSCS) is indicated in various clinical scenarios where vaginal delivery poses risks to the mother or fetus. Primary indications include fetal distress, characterized by abnormal fetal heart rate patterns suggesting compromised oxygenation, which necessitates prompt delivery to prevent hypoxia.[6] Failure to progress in labor, such as dystocia due to cephalopelvic disproportion or ineffective uterine contractions, also warrants LSCS to avoid prolonged labor and associated maternal exhaustion or infection.[6] Abnormal fetal presentations, including breech or transverse lie, increase the risk of cord prolapse or entrapment, making LSCS the preferred method for safe extraction.[6] Placental abnormalities like previa, where the placenta covers the cervical os, or abruption, involving premature separation, further justify LSCS to manage bleeding and ensure fetal viability.[6] Maternal conditions, such as severe preeclampsia with organ dysfunction or active genital herpes to prevent neonatal infection, are additional absolute indications.[1] Multiple pregnancies, particularly triplets or higher, often require LSCS due to risks of malpresentation and delivery complications.[6] Elective LSCS is recommended in select cases, including a history of previous LSCS with a low transverse uterine scar, where vaginal birth after Caesarean (VBAC) may carry rupture risks, leading to planned repeat surgery for safety.[7] Maternal request, supported by some guidelines after counseling on risks and benefits, may be considered without medical necessity, though not routinely encouraged.[7] In high-risk pregnancies, such as those with multiple gestations or scheduled for fetal anomalies, elective timing optimizes outcomes.[8] While LSCS is the standard approach, certain scenarios favor alternatives like classical vertical incision, particularly when the lower uterine segment is immature or inaccessible, such as in preterm deliveries at ≤30 weeks gestation, anterior placenta previa obscuring the segment, or maternal morbid obesity complicating access.[9] Uterine anomalies or large fibroids may also necessitate classical incision for better exposure.[9] Globally, LSCS accounts for over 90% of all Caesarean sections due to its lower risk of hemorrhage, infection, and future uterine rupture compared to classical methods.[10]Surgical Procedure
Preoperative Preparation
Preoperative preparation for a lower segment Caesarean section involves a systematic evaluation and optimization of the patient to ensure safety and efficacy during the procedure. This begins with comprehensive patient assessment, including obtaining informed consent after discussing the indications, risks, benefits, and alternatives to surgery, in alignment with patient autonomy.[1] The obstetrician reviews the specific indications, such as fetal distress or maternal conditions, to confirm the necessity of the procedure. Anesthesia options are evaluated, with regional anesthesia—such as spinal or epidural—preferred over general anesthesia for most cases due to reduced maternal and neonatal risks, unless an emergency necessitates rapid intervention.[1] Laboratory tests and imaging are essential to assess maternal and fetal status. Routine blood work includes a complete blood count to evaluate hemoglobin levels for anemia, a clotting profile to identify coagulopathy, and blood type and screen for potential transfusion needs.[1] Ultrasound imaging confirms fetal position, gestational age, and placental location to rule out anomalies like placenta previa that could influence surgical planning.[1] Physical preparation optimizes conditions to minimize complications. Patients are advised to fast from solid foods for at least 6 hours and clear liquids for 2 hours preoperatively, though this may be adjusted in emergencies; carbohydrate loading with clear fluids is encouraged for non-diabetic patients to reduce insulin resistance.[11] Intravenous access is established for fluid administration and medication delivery, and an indwelling urinary catheter is placed to monitor output and protect the bladder during surgery.[1] Prophylactic antibiotics, typically cefazolin (2 g IV for patients ≥80 kg or 1 g for <80 kg), are administered within 60 minutes before incision to reduce surgical site infections, with additional azithromycin if membranes have ruptured.[12] Skin preparation uses chlorhexidine-alcohol solution on the abdomen and, if indicated, vaginal cleansing to further prevent infections.[11] Measures against venous thromboembolism include pneumatic compression devices applied preoperatively for all patients undergoing Caesarean section.30518-4/fulltext) Antacids and H2-receptor antagonists are given to neutralize gastric pH and reduce aspiration risk.[11] A multidisciplinary team ensures coordinated care, comprising the obstetrician as surgeon, an anesthesiologist for analgesia management, a neonatologist for newborn resuscitation, nurses for monitoring and support, and surgical assistants.[1] The patient is positioned supine on the operating table with a left lateral tilt (15-30 degrees) using a wedge to relieve aortocaval compression by the gravid uterus, improving venous return and fetal oxygenation.[1]Operative Technique
The operative technique for a lower segment Caesarean section involves a systematic approach to access the uterus, deliver the fetus, and achieve secure closure while minimizing blood loss and tissue trauma.[1] This procedure is typically performed under regional anesthesia, such as spinal or epidural, to allow maternal participation if desired.[1] Abdominal AccessThe surgery begins with entry into the abdominal cavity, most commonly via a transverse Pfannenstiel incision placed 2-3 cm above the symphysis pubis, spanning 10-15 cm in length to provide adequate exposure.[1] In emergency situations or when greater access is required, a vertical midline laparotomy from the umbilicus to the pubic symphysis may be used instead.[1] The incision is extended through the subcutaneous fat using electrocautery or sharp dissection, followed by incision of the anterior rectus sheath.[13] The rectus muscles are separated in the midline with blunt finger dissection, and the peritoneum is incised transversely and reflected superiorly.[13] The urinary bladder is mobilized inferiorly by incising and reflecting the vesicouterine peritoneum to expose the lower uterine segment, reducing the risk of bladder injury.[1][6] Uterine Incision
A transverse incision is made in the lower uterine segment, positioned about 1 cm below the vesicouterine peritoneal reflection and well above the bladder attachment to the uterus.[6] This initial cut, approximately 3-4 cm long, is performed with a scalpel through the myometrium until just before the amniotic membranes, which are palpated to confirm fetal position and avoid injury.[6] The incision is then extended laterally to 10-15 cm using blunt finger dissection, curved scissors, or a finger fracture technique, with continuous suction to manage any bleeding.[1][6] In rare cases where the transverse incision proves inadequate for delivery, such as in malpresentation or cephalopelvic disproportion, it may be extended upward into a J-shaped or inverted T-shaped incision to provide additional space.[1] Fetal Delivery
Once the uterine incision is enlarged, the amniotic membranes are ruptured if still intact, and the fetal head is gently elevated from the pelvis using one hand while an assistant applies suprapubic pressure.[1] The head is delivered first, followed by external rotation and extraction of the shoulders and body; in breech presentations, gentle traction with Piper forceps may assist.[1] The umbilical cord is immediately clamped at two points, divided between them, and handed to the neonatal team for resuscitation if needed.[13] Throughout, the fetal lie is assessed by palpation to prevent inadvertent injury.[6] Placental Removal and Uterine Closure
The placenta is typically delivered spontaneously by gentle cord traction combined with fundal massage to encourage uterine contraction; if necessary, manual removal is performed by inserting a hand into the uterus to detach and extract it entirely, followed by inspection for retained fragments.[1] The uterine incision is repaired in one or two layers using absorbable synthetic sutures, such as 0 polyglactin 910 (Vicryl), with a continuous locking technique for the inner layer and interrupted or figure-of-eight sutures for hemostasis in the outer layer.[6][13] Temporary hemostatic control may involve applying Green Armytage forceps along the incision edges for 2-3 minutes to promote clotting before final suturing.[6] The uterus is then returned to the pelvic cavity. Abdominal Closure
Closure proceeds in layers: the vesicouterine peritoneum and parietal peritoneum are approximated with continuous absorbable 3-0 sutures if elected, though peritoneal closure is often omitted to reduce operative time.[1][13] The rectus fascia is closed with interrupted or continuous 0 absorbable sutures, the subcutaneous tissue is undermined if thick, and the skin is approximated with subcuticular sutures, staples, or adhesive strips.[1] The entire procedure generally takes 30 to 60 minutes, with fetal delivery occurring within the first 5-15 minutes.[14]