Fluid and electrolyte balance

Patients undergoing gynaecological surgery, excluding minor and day-case procedures, require intravenous (IV) fluid administration until oral fluid intake is fully resumed. The daily requirement of fluid should be calculated accurately and the patient should be monitored carefully to ensure adequate hydration. This is important to avoid fluid overload (which could lead to pulmonary oedema) or dehydration (which could result in renal tubular necrosis). When calculating the fluid intake, one should consider the normal fluid requirement (approximately 2.5 l/24 h), intraoperative blood loss and insensible losses (e.g. due to raised temperature). Other factors to be considered when calculating fluid intake include preoperative depletion of fluids, long operative procedures, pyrexia, fluid loss through drains, excessive vomiting, bowel distension, oral fluid intake, extravascular fluid accumulation (third space) and previous fluid replacement.

Urine output monitoring should be used to determine the status of the intravascular volume and total body water. The normal urine output is 30 ml/h. Patients voiding less than 17 ml/h are oliguric. Other clinical signs of dehydration include mucous membrane dryness, slow skin turgor, tachycardia and raised temperature. Patients should also be monitored for features of fluid overload such as jugular venous distension, mucous membrane turgor, pulmonary rales, third heart sound and pitting oedema. Central venous pressure monitoring should be considered when there is difficulty assessing intravascular volumes. Invasive direct measures of cardiac output that enable accurate measurement of intravascular filling (e.g. measurements of pulmonary wedge pressures and transoesophageal echo) are rarely required after gynaecological surgery.

Oliguria can be prerenal, renal or postrenal. Postoperative oliguria is most commonly prerenal and is caused by insufficient fluid replacement. This can be confirmed by a fluid challenge with the infusion of 250 ml of a colloid such as gelofusin over 15 min. Improvement of urine output after this fluid challenge confirms prerenal oliguria, which can be corrected by increasing the rate of IV fluid administration. If there is no improvement in urine output with the fluid challenge, the patient should be assessed for evidence of pulmonary oedema and renal impairment (due to tubular necrosis). In the elderly or those with known cardiac disease, fluid challenges should be given with caution as this may exacerbate pulmonary oedema.

If prerenal and renal causes of oliguria have been excluded, a postrenal aetiology such as ureteric obstruction should be considered. Diagnosis can be made with renal ultrasound. If this is inconclusive, ureteric catheters can be used for diagnosis and treatment.

The majority of gynaecological patients undergoing surgery are healthy and usually resume their diet within 24–48 h. Postoperative monitoring of electrolytes is therefore not required routinely in these patients. However, electrolyte imbalance may occur under certain circumstances such as persistent vomiting, prolonged IV fluid administration, and after surgery involving extensive tissue damage or excessive drainage from the surgical site. In addition, patients with renal impairment, diabetes or those receiving certain medications (e.g. potassium-sparing diuretics) are at increased risk of electrolyte disturbances. These patients should be monitored for electrolyte imbalance and treated promptly for any abnormality. Both hypo- and hyperkalaemia can result in cardiac arrhythmias and therefore require assessment by electrocardiogram (ECG). Hypokalaemia usually results from delayed oral intake or excessive vomiting. It can be corrected by increasing the potassium content of the IV fluid (20 mEq KCl/l). Hyperkalaemia can occur in patients undergoing extensive surgery due to shift of potassium from traumatized cells into the extracellular space. Moderate or severe hyperkalaemia (potassium level >6 mEq/l) is a medical emergency; if not corrected promptly, it can lead to severe cardiac arrhythmias and death. An input from the medical team should therefore be sought. It can be corrected by IV administration of glucose and insulin to promote potassium shift into the cells. Calcium gluconate is also given to protect the heart from dysrhythmias. Hyponatraemia is usually secondary to excessive fluid administration or absorption of excessive amounts of irrigating fluid during hysteroscopic surgery, and hypernatraemia is secondary to dehydration.

Bladder care

In women undergoing major gynaecological surgery, a urinary catheter is usually inserted just before the operation to keep the bladder empty throughout the procedure. This helps to minimize the risk of bladder injury and allows good access to the surgical field. Post operatively, the catheter is kept in place during the acute recovery phase for the patient’s comfort, to allow monitoring of urine output and to avoid urinary retention due to the general anaesthetic or pain. The catheter should be removed as soon as the patient is able to mobilize and void comfortably. Early removal of the catheter is important as prolonged catheterization may be associated with an increased risk of urinary tract infection (Schiøtz and Tanbo 2006). In patients who sustained a bladder injury during surgery, the catheter should be kept for 7–10 days to allow full healing of the bladder wall, and many gynaecologists would perform a systogram prior to removing the catheter.

Postoperative voiding difficulty is a common problem in gynaecological surgery, especially following bladder neck operations, and can be due to spasm, oedema or tenderness of parauretheral tissue. It is also common following radical hysterectomy due to extensive perivesical dissection that interferes with the nerve and blood supply to the bladder. Other contributing factors include cystitis and psychogenic factors. Failure to pass urine could also occur as a result of regional anaesthesia (which may cause bladder overdistension and atony) and abdominal pain, which may inhibit the initial voluntary phase of voiding. Following bladder neck surgery, most voiding difficulty resolves within 1 or 2 weeks of surgery, but up to 20% of women can continue with this problem for an extended period (up to 6 months) before being able to void normally (Smith and Cardozo 1997).

If the patient does not pass urine for 4–6 h after catheter removal, residual urine volume should be measured after micturition using a bladder ultrasound scan. This should also be performed in women undergoing bladder neck surgery or radical hysterectomy. Voiding difficulty is diagnosed if the residual volume is consistently greater than 100 ml. If this problem persists after several voiding attempts, a catheter should be inserted for 24 h. The catheter is then removed and further residual volume measurements are carried out. If still high, the patient should be allowed home with an indwelling catheter for 7–10 days. Failing this, the catheter could be left in the bladder for a longer period. Eventually, if voiding difficulty persists, the patient should be trained to perform intermittent self-catheterization.

A suprapubic catheter should be considered during surgery in patients expected to have postoperative voiding difficulty. This allows easier and more accurate measurement of residual volumes. The catheter is clamped and the patient is asked to void urine. This is followed by measurement of residual urine passing through the suprapubic catheter. Another advantage of this catheter is the reduced risk of urinary tract infections compared with the urethral catheter.

Drains

Although not necessary in the majority of routine gynaecological procedures, drains can be helpful in certain cases. The main indication for placing a drain during gynaecological surgery is surface oozing following extensive pelvic surgery such as adhesiolysis, treatment of extensive endometriosis or complicated hysterectomy. Drainage in these cases is necessary to prevent haematoma formation and to allow early recognition of significant postoperative internal haemorrhage. However, the drain should not be used as a substitute for meticulous intraoperative haemostatesis. Other indications for pelvic drainage include pelvic infection (e.g. tubo-ovarian abscess) and clotting disorders, which could result in persistent postoperative oozing.

Intraperitoneal (pelvic) drains have been associated with an increased incidence of infection, and should only be used when the benefits outweigh the risks. Evidence from recent randomized trials and systematic reviews is against the routine use of drains. A recent large randomized trial of drains compared with no drains following radical hysterectomy and pelvic lymph node dissection concluded that drains can be safely omitted in the absence of excessive bleeding during surgery or oozing at the end of surgery (Franchi et al 2007). A systematic review evaluating the value of routine suction drains after retroperitoneal lymphadenectomy in gynaecological tumours concluded that the prophylactic use of continuous suction drains is associated with a significant increase in morbidity and should be avoided (Bacha et al 2009). On the other hand, drainage of surgical wounds (especially clean-contaminated wounds) using a closed-suction system has been used prophylactically to reduce wound infection (Panici et al 2003).

There are two main types of drains: passive (non-suction) and active (suction). Passive drains, which drain by overflow assisted by gravity, are preferred for the peritoneal cavity, where soft tissue can block the fenestrations of suction drains. Passive drains should not be brought out through the incision, to avoid the risk of wound infection. Suction drains are sealed systems with a vacuum to drain a potential space created by surgery such as the subcutaneous or subfascial space. They are also used to drain lymphatic fluid from the groins after lymphadenectomy.

Early removal of drains is recommended to avoid infection and aid mobilization. The precise timing for removal of a drain should be determined on an individual basis and depends on the reasons for its insertion. Drains that were placed prophylactically to avoid the accumulation of blood, pus or lymph can usually be removed when drainage is <100 ml in 24 h, usually by 2 or 3 days after surgery. Drains placed for drainage of an abscess should be managed according to the resolution of the condition.

Postoperative pain management

Effective relief of postoperative pain is of paramount importance as it offers significant psychological and physiological benefits to the recovering patient. Not only does it mean a smooth postoperative course with earlier discharge from hospital, but it also helps to reduce the incidence of complications (Nagaratnam et al 2007). In addition, there is evidence that good pain relief can reduce the onset of chronic pain syndromes. Inadequate pain management could lead to reduced deep breathing, causing impaired oxygenation. It can also cause inability to cough and clear lung secretions which may lead to lung atelectasis. Pain reduces a patient’s mobility, leading to slower recovery and increased risk of morbidities such as deep vein thrombosis (DVT). The benefits of good postoperative pain management are summarized in Table 9.1.

Table 9.1 Benefits of effective postoperative pain relief

The first step in achieving good pain control is preoperative prediction and accurate postoperative assessment of the degree of pain. Such pain is subjective and can vary greatly in severity between patients from almost no pain to very severe pain. There are two main factors determining the degree of postoperative pain: firstly, the nature, extent and site of the surgery; and secondly, factors related to the patient including fear, anxiety and pain threshold. A previous experience of postoperative pain may also infuence the patient’s expectation and perception of pain. It is therefore important to plan postoperative pain management through consultation between the surgeon and the anaesthetist based on the predicted pain severity. It is also important to explain to the patient the expected degree of pain and the steps that will be taken to ensure effective pain relief afterwards. It is usually helpful to establish the patient’s expectations of pain before surgery. This approach has been shown to minimize the patient’s fear and anxiety from pain and to reduce the requirement for postoperative analgesia (Karanikolas and Swarm 2000).

Methods of assessment

After surgery, pain can be assessed using one of several methods such as the visual analogue scale (VAS) or the verbal response score (VRS). With the VAS, the patient chooses a number between 0 and 10 to represent her pain. Zero indicates no pain and 10 means pain as severe as can be imagined. The VRS utilizes a simple five-point scale which either correlates pain severity to words (no pain, mild, moderate, severe, excruciating) or to a number (0–4). The pain should be assessed at regular intervals, preferably charted in graphical form and should form part of the routine postoperative observation.

The analgesic ladder

The World Federation of Societies of Anaesthesiologists’ analgesic ladder, which has been developed to treat acute pain, can be utilized for postoperative pain (Charlton 1997; Figure 9.1). In women undergoing major gynaecological surgery, the initial pain can be expected to be severe and may need injections of strong opioids [e.g. morphine, preferably by a patient-controlled analgesia (PCA) system], which can be combined with local anaesthesia. As pain decreases with time, analgesia can be stepped down and parenteral opioids can be gradually replaced by the oral route. Strong oral opioids (e.g. oromorph) can be given, to be gradually replaced with a combination of peripherally acting agents (e.g. paracetamol and non-steroidal anti-inflammatory drugs) and weak opioids (e.g. codeine phosphate). The final step is when the pain can be controlled by peripherally acting agents alone.

Figure 9.1 The World Federation of Societies of Anaesthesiologists’ analgesic ladder. Local anaesthesia indicates epidural, spinal or peripheral nerve or wound block. NSAID, non-steroidal anti-inflammatory drug.

Source: Charlton JE (1997) The management of postoperative pain. Update in Anesthesia 7: 2–17 (www.anaesthesiologists.org).

Wound care

Good wound care will promote healing and minimize complications such as infection, haematoma formation or dehiscence. Wound care begins during surgery with careful handling of tissues, avoidance of cautery for skin incision, meticulous haemostasis, good closure techniques and avoidance of excessive traction on the skin edges (Boesch and Umek 2009). At the end of surgery, a wound dressing is applied, mainly to cover the fresh wound to prevent seepage of serum or blood, but this does not have any protective effect against infection. It should be removed on the first postoperative day when the wound has become dry. Any serous or serosanguinous discharge can be squeezed out by gentle pressure on the wound edges. Patients can be allowed a shower, but should keep the wound dry and clean. Sutures and staples can be removed from transverse wounds after 4–5 days, but vertical wounds usually require 7–10 days to heal.

Postoperative feeding