Chapter 48 Cathleen Mochal-King Department of Clinical Sciences, College of Veterinary Medicine, Mississippi State University, Starkville, Mississippi, USA A cesarean section is a surgical procedure that is utilized to relieve, or in some cases prevent, dystocia.1–3 Causes of dystocia are categorized as maternal or fetal and are covered in Chapter 46. Indications for cesarean sections include dystocia cases in which the calves are alive and valuable that cannot be delivered vaginally, and/or dystocia cases in which the calf is dead but delivery by another means jeopardizes the life or future fertility of the cow. A cesarean section (C-section) is rarely completed under strict asepsis, but this is not due to the fact that it is so often performed in field settings. This is even the case when a C-section is performed in a hospital setting in a surgery room. A C-section is classified as a clean contaminated procedure. This classification describes a surgery where a nonsterile body cavity is entered under a controlled condition without unusual contamination; in this case the uterus is the nonsterile cavity.4 Furthermore, Mijten et al.4 demonstrated that uterine cultures collected during C-sections often resulted in positive bacterial cultures, with 83% of these samples heavily contaminated. This leads to the conclusion that endogenous bacterial contamination of the surgical site from the hysterotomy is likely inevitable.4 The fact that bacterial contamination is probable does not excuse inattention to surgical preparation or to cleanliness. Therefore it is important to minimize exogenous bacterial contamination through an efficient and quick performance of the procedure. Additionally, my recommendation is to administer antimicrobials preoperatively to diminish postoperative complications as a result of the endogenous contamination. Success of a C-section is defined as a live cow with a live calf, and the ability to rebreed the cow. These outcomes are dependent on a number of variables in addition to the surgeon’s skill. Many of these variables are beyond the surgeon’s control. A realistic approach to this surgery is to evaluate the case, the surgical theater, the cow’s size, her condition and attitude, the owner’s expectations, and the prognosis. Then tailor your plan to the circumstances and conditions presented. For example, there are several surgical approaches that have been described. It is typical for a surgeon to identify more with one approach than another due to preference and comfort level. However, there are specific case presentations for which a particular approach offers definite advantages. Newman5 discusses the importance of case selection when determining the surgical approach. To aid a surgeon’s treatment plan, Newman categorizes the C-section procedure as elective, emergency nonemphysematous, and/or emergency emphysematous. This categorization of the procedure is relative to the condition of the calf and its effects on prognosis and case management. The elective category allows the surgeon to choose to some extent the time and the place that the surgery will be performed as well as the ability to make other preparations. Thus this category carries the best prognosis for success, the exception being when the timing of the procedure might be elective but is performed due to an infirmity of the dam (fractured limb, etc.). The emergency obstetric case in which a decision to proceed to C-section is made early in the course of the dystocia without excessive manipulation and particularly while the calf is still alive likewise carries a very good prognosis. For both of these case categories only basic postoperative management is required. The situation in which the decision to proceed to C-section to deliver an emphysematous calf should carry with it the expectation or at least readiness for complications, significant postoperative care, and a guarded prognosis. Sometimes the decision to proceed to C-section occurs after extensive obstetric manipulation or even partial fetotomy efforts. This, in my opinion, carries a less favorable prognosis than the emphysematous category. Indications for an elective C-section are a valuable fetus, complicating factors such as a dam with a prepartum vaginal prolapse, a small or malformed pelvis, a recent life-threatening condition, and/or a prolonged gestation.1–3 In any case, a history that includes breeding date or embryo transfer date should help assess the expected calving date. Calves born less than 2 weeks prematurely should not be unduly at risk for complications or fatalities (see Chapter 44). A C-section can be scheduled without respect to the initiation of parturition. Research performed comparing the timing of an elective C-section with respect to the stage of parturition revealed that the presence of full cervical dilatation before performing the C-section allowed better postnatal respiratory and metabolic adaptation in full-term calves.6 When comparing elective C-section with vaginal delivery it is believed that aspects of vaginal delivery aid calves in transitioning from the womb. Specifically, in a study in which the hematologic profiles of calves delivered by elective C-section were compared with those of calves delivered by unassisted vaginal delivery, C-section calves were uniformly more hypoxic and had a greater likelihood of experiencing respiratory distress.7 Because of the experimental design, all the deliveries (both vaginal and C-section) were uncomplicated. The hypoxia in the C-section calves was not due to, or associated with, respiratory or metabolic acidosis. The authors hypothesized that the unassisted vaginal delivery calves benefited from both the compression of the fetal thorax that occurs during transit through the pelvis and the temporary suspension by the hindlimbs improving post-delivery oxygenation.7 Both of these events occur during spontaneous vaginal delivery. To ameliorate these disadvantages, one option is to administer dexamethasone (20 mg) with or without a prostaglandin to induce parturition (see Chapter 44). This of course makes the C-section less “elective.” Certain techniques can be performed on the neonate after delivery to improve respiratory function. These are likely beneficial following the delivery of any calf. Carefully lifting the newborn by their rear legs, as illustrated in Figure 48.1, for a few seconds should correspond with the stage of normal vaginal delivery in which the calf is momentarily suspended. This must be performed without swinging or shaking the calf, which although a common practice can be injurious to the calf. Following suspension, place the newborn in lateral recumbency. Grasp the thoracic limb, elevating and lowering the limb. This limb motion lifts the calf’s chest off the ground and facilitates thoracic excursions. Repeat this motion three to four times. Additionally or alternatively respiratory efforts can be stimulated by “tickling” the nasal openings of the newborn with a straw or twig inducing a sneeze, further aiding airway clearance (Figure 48.2). Figure 48.1 Lifting newborn by rear limbs will duplicate aspects of natural vaginal delivery. Do not shake or swing calf. Figure 48.2 Respiratory efforts can be stimulated by “tickling” the nasal openings of the newborn with a straw or twig, inducing a sneeze and further aiding airway clearance. Technique demonstrated here with an enteral feeding tube. For prognostic reasons the decision to perform a C-section must occur in a timely manner. Several clinical signs or circumstances can direct a quick decision to proceed to surgery. The first clinical assessment indicating a C-section is the obviously small heifer with a small or abnormally shaped pelvis.1–3 Next, as obstetric manipulations are made and extraction of the calf is being attempted, pressure on the proximal aspect of the fetal forelimbs by the pelvis resulting in crossing of the forelimbs is an indication of fetal–maternal pelvic size incompatibility. Additionally, failure to progress in delivery of the calf is an indication for surgery. Clinicians should have a preset metric (time frame) for progress during obstetric procedures. For example, if obstetric manipulation is being made with no progress for a period of 10 min, then one must proceed to surgery. This is not to say that the calf must be delivered in that or another designated time frame, but that “progress” must be made. In the case where the fetus is dead, and especially if it is emphysematous, the prognosis is less favorable. Case management and treatment plans must be discussed with the owner with regard to outcome prior to proceeding. Although a fetotomy is an option when the calf is dead, certain clinical presentations favor C-section. C-section is the treatment of choice for the emphysematous breech, the unreducible uterine torsion, an undilated cervix, preexisting vaginal or cervical trauma from lay delivery attempts, and uncooperative patient temperament.1–3,5 These cases, as stated previously, dictate aggressive postoperative care and an increased risk of complications Surgeon preference, patient temperament, environment, and case presentation dictate the surgical approach selected. C-sections may be performed under standing sedation or cast in recumbency. The surgical approach determines the type of restraint employed and the method of anesthesia, whether regional or general. Surgical approaches that have been utilized for C-section are the flank (left or right), the ventral midline, and the paramedian. There are no advantages for a paramedian over the ventral midline8 so that approach is not covered here. The standing left flank approach is the most common surgical technique for C-section in cattle. The left flank approach is superior in that the rumen prevents prolapse of intestinal loops from the incision. This standing procedure is not recommended in animals that are likely to become recumbent during the surgery due to exhaustion, hypocalcemia, obturator nerve paralysis, and/or highly fractious nature.2 The standing right flank approach has limited indications. It can be utilized when there is rumenal distension or adhesions on the left side from a previous left flank surgery.9
Obstetrics: Cesarean Section
Introduction
Elective C-section
Emergency C-section
Surgical approaches
Standing left flank
Standing right flank
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