Various complications may occur after surgery. Understanding their causes, clinical manifestations, and aligned prevention and treatment strategies is an essential aspect of postoperative care. Postoperative complications can stem from the underlying condition, the surgical procedure, or unrelated factors. In some cases, pre-existing complications may trigger secondary complications (e.g., postoperative hemorrhage leading to myocardial infarction).
Postoperative Hemorrhage
Inadequate intraoperative hemostasis, uncontrolled bleeding from the surgical site, dilation of previously spasmed small arterial stumps, loosening of ligatures, and coagulation disorders are all possible causes of postoperative hemorrhage.
Postoperative hemorrhage may occur at the surgical incision, within hollow organs, or in body cavities. If shock develops within the first 24 hours after abdominal surgery, it raises the suspicion of internal bleeding. The clinical presentation includes tachycardia, hypotension, reduced urine output, and peripheral vasoconstriction. Continued bleeding may lead to an increase in abdominal girth. Bedside ultrasound and diagnostic peritoneal aspiration can confirm the diagnosis. In thoracic surgeries, internal bleeding is suggested if chest drain output exceeds 100 ml per hour persistently. A chest X-ray may reveal pleural effusion. Postoperative hemorrhage should be considered when central venous pressure drops below 0.49 kPa (5 cmH2O), urine output is less than 25 ml per hour, and signs of shock persist, worsen, or recur despite adequate blood and fluid infusion. In such cases, reoperation for hemostasis is typically required.
Postoperative Fever and Hypothermia
Fever
Fever is the most common postoperative symptom, with approximately 72% of patients experiencing a body temperature above 37°C and 41% exceeding 38°C. Postoperative fever does not always indicate infection. Non-infectious fevers typically present earlier than infectious fevers (averaging 1.4 days after surgery versus 2.7 days).
Non-infectious causes of fever include lengthy surgeries (lasting more than two hours), extensive tissue trauma, intraoperative blood transfusion, drug allergies, and hepatotoxicity induced by anesthetics like halothane or enflurane. Temperatures below 38°C generally require no treatment. Temperatures exceeding 38.5°C and resulting in patient discomfort warrant physical cooling and symptomatic management with closely monitored observation.
Risk factors for infectious fever include frailty, advanced age, poor nutritional status, diabetes mellitus, smoking, obesity, use of immunosuppressants, or pre-existing focal infections. Neglect in administering prophylactic antibiotics may also contribute. Surgical-related risk factors include insufficient hemostasis, residual dead space, and tissue trauma. In addition to incision site and deep tissue infections, common causes of postoperative infectious fever include atelectasis, pulmonary infections, urinary tract infections, and suppurative or non-suppurative phlebitis.
Hypothermia
Mild hypothermia is a common postoperative complication, often caused by anesthetics interrupting thermoregulatory processes, heat loss during thoracic or abdominal surgery, or infusion of cold fluids and stored blood. Mild hypothermia usually has no significant impact on the body. However, severe hypothermia can lead to a range of complications, including increased peripheral vascular resistance, reduced cardiac contractility, decreased cardiac output, suppressed neural activity, and coagulopathy due to impaired thrombin function. Severe hypothermia is often associated with extensive surgeries, especially those involving multiple injuries or requiring large volumes of cold fluids and stored blood.
Intraoperative temperature monitoring is essential. The infusion of cold fluids and blood should be conducted using warming devices, and body cavities may require repeated irrigation with warm saline when necessary. Postoperatively, maintaining patient warmth is critical. These measures are effective in preventing postoperative hypothermia.
Respiratory Complications
Respiratory complications rank as the second most common cause of postoperative mortality. Patients over 60 years of age, those with reduced respiratory system compliance, increased residual lung volume, and enlarged dead space, as well as those with a history of chronic obstructive pulmonary disease (COPD), asthma, or pulmonary fibrosis, are at heightened risk for postoperative respiratory complications.
Atelectasis
The incidence of atelectasis is approximately 25% after upper abdominal surgery and is more common in elderly, obese, chronic smokers, and patients with pre-existing respiratory conditions. Atelectasis often occurs within the first 48 hours post-surgery, with 90% of associated fevers linked to this complication. If it persists beyond 72 hours, secondary pulmonary infections are likely.
Prevention and treatment involve chest and back percussion, encouraging coughing and deep breathing, and nasotracheal suctioning to clear secretions. For patients with severe COPD, nebulized bronchodilators and mucolytic agents can provide relief. In cases of airway obstruction, bronchoscopy may be necessary.
Postoperative Pulmonary Infections
Risk factors for postoperative pulmonary infections include atelectasis, aspiration of foreign material, and excessive secretions. Patients with intra-abdominal infections requiring prolonged mechanical ventilation are at the highest risk. Endotracheal intubation can damage the mucociliary transport system, while oxygen therapy, pulmonary edema, aspiration, and corticosteroid use may impair alveolar macrophage activity. More than 50% of postoperative pulmonary infections are caused by gram-negative bacilli.
Pulmonary Embolism (PE)
Pulmonary embolism refers to a clinical and pathophysiological syndrome characterized by obstruction of the pulmonary artery or its branches by endogenous or exogenous emboli, leading to pulmonary circulation disorders. It includes pulmonary thromboembolism, fat embolism syndrome, amniotic fluid embolism, air embolism, tumor embolism, and bacterial embolism. Risk factors for pulmonary embolism include age (over 50 years), deep vein thrombosis of the lower limbs, trauma, soft tissue injury, burns, cardiopulmonary disease, obesity, certain hematological disorders, and metabolic diseases such as diabetes mellitus.
Clinical manifestations include sudden onset of dyspnea, chest pain, hemoptysis, and syncope; unexplained acute right heart failure or shock, decreased oxygen saturation, systolic murmurs in the pulmonary valve area, and an accentuated P2 sound. Treatment involves several approaches:
- General management includes intensive care monitoring, strict bed rest, and the use of sedatives or analgesics to alleviate anxiety or distress.
- Respiratory support includes oxygen therapy and mechanical ventilation via endotracheal intubation.
- Circulatory support is provided as needed.
- Thrombolytic and anticoagulation therapies are administered. The prognosis depends on the severity of respiratory dysfunction.
Postoperative Infections
Abdominal Abscess and Peritonitis
Symptoms include fever, abdominal pain, abdominal tenderness, and leukocytosis. Diffuse peritonitis requires emergency exploratory laparotomy. For localized infections, abdominal and pelvic ultrasound or CT scans often aid in diagnosis. Once an abdominal abscess is located, ultrasound-guided percutaneous drainage may be performed, and open drainage may be necessary in some cases. Antibiotics should be selected based on bacterial culture sensitivity testing for targeted treatment.
Fungal Infections
Fungal infections are primarily caused by Candida species and often occur in patients who have been on long-term broad-spectrum antibiotics. Persistent fever without an identifiable pathogen indicates the possibility of fungal infection. Fungal-related tests are necessary for diagnosis, and antifungal treatments should be administered according to test results.
Incisional Complications
Hematoma, Hemorrhage, and Blood Clots
These are the most common complications. Risk factors include the use of aspirin or low-dose heparin, pre-existing coagulation disorders, severe postoperative coughing, and elevated blood pressure. Symptoms include swelling and bulging at the incision site, changes in color, and sometimes blood leakage through the sutures. Hematomas in areas like the neck after surgeries such as thyroidectomy, parathyroidectomy, or carotid artery procedures are particularly dangerous, as rapid hematoma expansion may compress the airway, leading to asphyxia. Small hematomas may be reabsorbed but increase the risk of wound infection. Treatment involves sterile removal of clots, ligation of bleeding vessels, and re-suturing of the incision.
Seroma
Seromas refer to fluid accumulation in a wound that is not blood or pus. This is often associated with the cutting of numerous lymphatic vessels, such as in mastectomies or groin surgeries. Seromas impede wound healing and increase infection risk. Subcutaneous seromas may be aspirated with a needle, and compression dressings can help reduce lymph leakage and fluid reaccumulation. Seromas in the groin, often following vascular surgery, usually resolve spontaneously, as needle aspiration risks vascular injury and infection. Persistent or leaking seromas require wound re-exploration and ligation of lymphatic vessels.
Wound Dehiscence
Wound dehiscence refers to the partial or complete separation of sutured layers of a surgical incision. Full-thickness abdominal wall dehiscence is often accompanied by protrusion of abdominal organs. Dehiscence can occur at any incision site but is most common in abdominal areas and at joints. Causes include:
- Poor nutrition leading to reduced tissue healing capacity.
- Suturing defects, such as inadequate knot tightness or incomplete tissue approximation.
- Sudden increases in intra-abdominal pressure due to severe coughing or abdominal distension.
Wound dehiscence most often occurs within the first postoperative week and typically manifests when patients suddenly strain their abdomen, experiencing incision pain followed by a sensation of release and leakage of pale red fluid. Deep tissue separation with intact skin sutures is classified as partial dehiscence, while complete layer separation, with protrusion of intestinal loops or omentum, constitutes complete dehiscence.
Preventive measures include avoiding dead space during wound closure and not routing drains through the incision. Additional strategies are:
- Incorporating full-thickness abdominal-wall retention sutures during closure.
- Ensuring incision closure is performed under sufficient anesthesia and abdominal wall relaxation to avoid tearing deeper tissues.
- Promptly managing abdominal distension.
- Encouraging a supine position during coughing to reduce the sudden descent of the diaphragm and spikes in intra-abdominal pressure.
- Applying appropriate abdominal compression dressings to mitigate risks.
Complete wound dehiscence requires immediate sterility measures, including placing a sterile dressing over the wound, followed by re-suturing under optimal anesthesia conditions. Retention sutures should be applied. Post-reclosure, intestinal paralysis commonly occurs, necessitating nasogastric decompression.
Incisional Infections
Incisional infections are characterized by localized redness, swelling, heat, pain, and tenderness at the wound site, often accompanied by discharge (in superficial wound infections). Fever and leukocytosis may or may not be present. Management focuses on removing sutures at the site of redness and swelling to allow drainage of purulent fluid, and conducting bacterial cultures. Common pathogens in clean surgical wound infections include Staphylococcus or Streptococcus species, while infections in wounds from perineal or intestinal surgeries may be caused by intestinal flora or anaerobes. Antimicrobial therapy should be selected accordingly. Severe infections involving fascia and muscle layers require emergency incision and debridement, along with the administration of intravenous broad-spectrum antibiotics.
Urinary System Complications
Urinary Retention
Urinary retention is a relatively common postoperative complication, particularly in elderly patients, individuals undergoing pelvic or perineal surgeries, or those receiving spinal anesthesia, which may suppress the micturition reflex. Other factors include incision pain causing reflexive spasms of the bladder and posterior urethral sphincters, as well as a patient’s unfamiliarity with urinating while lying in bed. If no urination occurs 6–8 hours after surgery, or if urination is limited to small amounts at frequent intervals, percussion over the suprapubic area may reveal a distinct dullness, indicating urinary retention requiring timely intervention. Emotional reassurance can help alleviate anxiety. In the absence of contraindications, patients may be assisted to sit on the edge of the bed or stand to encourage urination. If these measures are ineffective, catheterization is necessary. When urinary retention persists for a prolonged period with catheter drainage exceeding 500 ml, an indwelling catheter may be retained for 1–2 days to help restore detrusor muscle function in the bladder wall. In cases of organic disorders, such as presacral nerve damage or prostatic hyperplasia, catheterization may need to be extended to 4–5 days.
Urinary Tract Infections
Lower urinary tract infections are among the most common hospital-acquired infections. Pre-existing urinary tract infections, urinary retention, and various urological procedures are major contributing factors. Among patients with short-term bladder catheterization (less than 48 hours), approximately 5% develop bacteriuria, although only 1% develop clinical symptoms. Acute cystitis is characterized by frequent urination, urgency, dysuria, difficulty urinating, and sometimes mild fever. Acute pyelonephritis presents with high fever, flank pain, and tenderness. Urinalysis reveals significant leukocytes and pus cells, and bacterial cultures confirm the diagnosis.
Preventive measures involve maintaining strict aseptic technique, minimizing contamination of the urinary system, and promptly addressing urinary retention. Treatment strategies include providing adequate fluid intake, ensuring complete bladder drainage, and employing targeted anti-infective therapy.