Diagnose von Aszites
So wird die Flüssigkeitsansammlung im Bauch erkannt
Aszites ist in vielen Fällen ein Zeichen für eine ernsthafte Grunderkrankung und sollte daher frühzeitig
untersucht werden. Eine sorgfältige Diagnose ist entscheidend, um die Ursache der Flüssigkeitsansammlung
zu bestimmen und die bestmögliche Behandlung einzuleiten. Dabei kommen verschiedene
Untersuchungsmethoden zum Einsatz, die von einer körperlichen Untersuchung bis hin zu bildgebenden
Verfahren und Laboranalysen der Aszitesflüssigkeit reichen.
Ascites diagnosis
How to recognise fluid build-up in the abdomen
In many cases, ascites is a sign of a serious underlying condition and should therefore be investigated at an early stage. A thorough diagnosis is crucial for determining the cause of the fluid build-up and initiating the best possible treatment. Various investigative methods are used, ranging from a physical examination to imaging procedures and laboratory analyses of the ascites fluid.
Physical examination
Initial indications based on visual and tactile examination
Even the external signs of ascites can provide the doctor with valuable clues about the condition. That is why the examination begins with a thorough inspection of the abdomen.
What does the doctor look for when examining the abdomen?
Increase in waist circumference
A steadily increasing swelling of the abdomen may indicate fluid retention, particularly if no corresponding weight gain due to fat or muscle mass would be expected.
Bulging of the abdomen when lying down
When lying down, the fluid in the abdominal cavity spreads out to the sides, causing the flanks to protrude. This phenomenon is a classic indication of significant fluid accumulation.
Skin that appears taut, possibly with stretch marks
The skin may become taut due to the increasing volume of fluid, which can cause stretch marks to form or stretch existing scars.
Protruding navel
In cases of severe ascites, the pressure in the abdominal cavity can be so high that the navel bulges outwards or, in rare cases, an umbilical hernia may even develop.
Following the visual examination, the doctor will carry out a physical examination involving palpation and percussion. During this, the doctor will gently feel the abdomen to check whether it is soft or tense and whether there is any pain. Percussion (tapping the abdomen) is particularly important, as fluid conducts sound differently from air or solid organs. If there is fluid in the abdominal cavity, the doctor may hear a characteristic muffled sound, which changes when the patient changes position.
These simple yet effective diagnostic methods often provide the first crucial indications of whether ascites is present. This is followed by targeted imaging and laboratory tests to determine the cause of the ascites and plan further treatment.
Ultraschalluntersuchung
Die zuverlässigste Methode zur Erkennung von Aszites
Die Ultraschalluntersuchung (Sonographie) ist am häufigsten eingesetzte Methode zur Diagnostik von Aszites. Bereits geringe Flüssigkeitsmengen ab 50–100 ml können im Bauchraum sichtbar gemacht werden, was sie zu einem unverzichtbaren Instrument für die frühzeitige Erkennung von Aszites macht.
Der Ultraschall liefert nicht nur einen direkten Nachweis der Flüssigkeit, sondern ermöglicht auch eine detaillierte Beurteilung der umliegenden Organe. So kann der Arzt erkennen, ob der Aszites möglicherweise durch eine Lebererkrankung, eine Krebserkrankung oder eine Herzschwäche verursacht wird.
Ultrasound scan
The most reliable method for detecting ascites
Ultrasound (sonography) is the most commonly used method for diagnosing ascites. Even small amounts of fluid, as little as 50–100 ml, can be visualised in the abdominal cavity, making it an indispensable tool for the early detection of ascites.
Ultrasound not only provides direct evidence of the fluid but also allows for a detailed assessment of the surrounding organs. This enables the doctor to determine whether the ascites may be caused by liver disease, cancer, or heart failure.
What can be specifically identified using ultrasound?
A particular advantage of ultrasound is that it can be performed quickly, painlessly, and without exposure to radiation. The examination is usually carried out whilst the patient is lying down, with a transducer coated in gel being moved across the abdomen. In specific cases, colour-coded Doppler ultrasound may be used to assess blood flow in the vessels, particularly where portal hypertension is suspected (elevated blood pressure in the portal vein, common in liver cirrhosis).
As ultrasound is a safe and non-invasive method, it forms part of the standard diagnostic procedure for ascites and is often the first imaging test carried out to plan further treatment. In some cases, however, additional tests such as a CT or MRI scan are necessary if the cause of the ascites remains unclear or if a tumour is suspected.
CT und MRT
Detaillierte Bildgebung bei unklarer Ursache
Während Ultraschall oft ausreicht, um Aszites zu erkennen, gibt es Fälle, in denen eine genauere Untersuchung erforderlich ist – insbesondere, wenn die Ursache unklar bleibt oder der Verdacht auf eine Krebserkrankung besteht. In solchen Situationen kommen Computertomographie (CT) oder Magnetresonanztomographie (MRT) zum Einsatz. Diese Verfahren liefern hochauflösende Bilder der inneren Organe und ermöglichen eine präzisere Beurteilung des Bauchraums.
Was kann durch CT und MRT festgestellt werden?
Beurteilung von Tumoren, Metastasen oder Organveränderungen
Falls der Aszites durch Krebs verursacht wird, können CT und MRT helfen, die genaue Lage und Größe von Tumoren oder Metastasen zu bestimmen. Dies ist besonders wichtig für die weitere Therapieplanung.
Detaillierte Darstellung von Blutgefäßen und Lymphbahnen
Ein gestörter Lymphabfluss oder eine erhöhte Durchlässigkeit der Gefäße kann zur Bildung von Aszites beitragen. CT- und MRT-Aufnahmen mit Kontrastmittel zeigen, ob Gefäße blockiert sind oder krankhafte Veränderungen vorliegen.
CT and MRI
Detailed imaging when the cause is unclear
Whilst ultrasound is often sufficient to detect ascites, there are cases where a more detailed examination is required – particularly if the cause remains unclear or if cancer is suspected. In such situations, computed tomography (CT) or magnetic resonance imaging (MRI) is used. These procedures provide high-resolution images of the internal organs and allow for a more precise assessment of the abdominal cavity.
What can be detected using CT and MRI scans?
Assessment of tumours, metastases or organ changes
If the ascites is caused by cancer, CT and MRI scans can help to determine the exact location and size of tumours or metastases. This is particularly important for planning further treatment.
Detailed imaging of blood vessels and lymphatic vessels
Impaired lymphatic drainage or increased vascular permeability can contribute to the formation of ascites. CT and MRI scans using contrast agents reveal whether vessels are blocked or if there are any pathological changes.
CT or MRI – which method is better?
A CT scan (computed tomography) is often used to get detailed images of the inside of the body. It is especially helpful for identifying tumors, metastases, or signs of inflammation. In many cases, a contrast agent is given through a vein to make organs and blood vessels easier to see. The scan itself only takes a few minutes. Because it uses X-rays, it is used when specifically needed.
An MRI scan (magnetic resonance imaging) is used when more detailed images of soft tissues are required, for example when examining the liver or pancreas. Instead of X-rays, MRI uses magnetic fields, which means there is no radiation exposure. However, the examination usually takes longer than a CT scan.
When is a CT or MRI scan recommended?
If the cause of the ascites remains unclear.
If cancer or metastases are suspected.
For the assessment of changes in blood vessels or lymphatic vessels.
If the ultrasound does not provide clear results.
In cases of malignant ascites, which is caused by cancer, a CT scan can provide important information about how the disease is affecting the body and how it may be developing over time.
These imaging results help the treating doctor choose the most appropriate treatment approach. This may include medication, drainage to relieve fluid build-up, or targeted cancer treatment.
Aszitespunktion
Entnahme und Untersuchung der Flüssigkeit
Wenn größere Mengen Aszites vorliegen oder die Ursache der Flüssigkeitsansammlung unklar bleibt, kann eine Aszitespunktion (Parazentese) durchgeführt werden. Dabei wird mit einer dünnen Nadel unter sterilen Bedingungen Flüssigkeit aus dem Bauchraum entnommen. Diese Flüssigkeit wird anschließend im Labor analysiert, um Hinweise auf die zugrunde liegende Erkrankung zu erhalten. Die Aszitespunktion ist besonders wichtig, um zwischen verschiedenen Aszitesformen zu unterscheiden, etwa ob es sich um eine leberbedingte, entzündliche oder krebsbedingte Ursache handelt. Dennoch empfehlen wir einen Dauerdrainagekatheter so früh wie möglich zu implantieren, um für eine schnelle Symptomlinderung und bessere Lebensqualität zu sorgen.
Paracentesis (drainage of fluid from the abdomen)
Collection and analysis of the fluid
If larger amounts of fluid build up in the abdomen, or if the cause is not yet clear, a procedure called paracentesis (drainage of fluid from the abdomen) may be performed.
During this procedure, a thin needle is used under sterile conditions to remove fluid from the abdomen. The fluid is then analyzed in a laboratory to help understand the underlying cause.
Paracentesis is especially useful for distinguishing between different types of ascites, for example whether it is related to liver disease, inflammation, or cancer.
For patients who need ongoing drainage, an indwelling catheter may be considered as an option to help manage symptoms and support quality of life.
How does paracentesis work?
The procedure is usually carried out on an outpatient basis and takes only a few minutes.
The patient lies relaxed in a comfortable position, usually half-sitting or lying on their side.
The puncture site on the abdomen is carefully disinfected and a local anaesthetic is administered.
Fluid is withdrawn using a fine needle – either for diagnostic analysis or, in cases of severe ascites, to relieve symptoms through therapeutic puncture.
After the sample has been taken, the puncture site is covered with a sterile dressing.
Which parameters are measured in an ascites analysis?
The fluid that has been drained is examined in detail in the laboratory to identify the cause of the ascites.
Protein level (Serum-Ascites Albumin Gradient, SAAG):
This is one of the most important values used to help understand the cause of ascites. It helps distinguish whether the fluid build-up is related to liver disease or to inflammation or cancer.
• A SAAG value above 1.1 g/dl usually indicates increased pressure in the liver (for example in liver cirrhosis).
• A SAAG value below 1.1 g/dl may suggest an inflammatory or cancer-related cause.
Microbiological examination (testing for infection):
If an infection is suspected, the fluid can be tested for bacteria or other microorganisms.
Cytological examination (testing for cancer cells):
If ascites caused by cancer is suspected, the fluid can be examined for the presence of cancer cells.
This analysis can provide important information, especially in cases of stomach, ovarian, or pancreatic cancer.
Cell count and signs of inflammation:
An increased number of white blood cells in the fluid may indicate an infection in the abdomen, such as bacterial peritonitis.
When is paracentesis needed?
The fluid that has been drained is examined in detail in the laboratory to identify the cause of the ascites.
If the cause of the fluid build-up is not yet clear.
If malignant ascites is suspected.
If an infection is suspected (e.g. spontaneous bacterial peritonitis).
If large amounts of fluid cause symptoms such as shortness of breath or discomfort (to relieve symptoms).
The test results provide important information to help guide further treatment. This may include medication, treatment of an infection, or drainage of the fluid to help relieve symptoms.
Blutuntersuchungen
Weitere Hinweise auf die Ursache
Zusätzlich zur Untersuchung der Aszitesflüssigkeit gibt eine Blutanalyse wichtige Informationen zur Grunderkrankung. Typische Laborwerte, die überprüft werden, sind:
Leberwerte (z. B. Albumin, Bilirubin, GPT, GOT, Gamma-GT, INR) → Hinweis auf eine Leberzirrhose.
Herzwerte (BNP, NT-proBNP) → Hinweis auf eine Herzinsuffizienz.
Nierenwerte (Kreatinin, Harnstoff, Elektrolyte) → Beurteilung der Nierenfunktion.
Tumormarker (z. B. CEA, CA-125, AFP) → Hinweise auf eine mögliche Krebserkrankung.
Blood tests
Further clues as to the cause
In addition to examining the ascites fluid, a blood test can provide important information about the underlying condition. Common values that are checked include:
Liver function tests (e.g. albumin, bilirubin, GPT, GOT, gamma-GT, INR):
These values can provide information about how well the liver is working and may indicate conditions such as liver cirrhosis.
Heart-related blood tests (e.g. BNP, NT-proBNP):
Kidney function tests (e.g. creatinine, urea, electrolytes):
These values help assess how well the kidneys are working.
Tumor markers (e.g. CEA, CA-125, AFP):
These values can provide information that may suggest the presence of a cancer-related condition.
Conclusion
A clear diagnosis helps guide the most appropriate treatment.
Ascites is often a sign of an underlying condition. To understand the cause, a thorough assessment is usually needed. This may include a physical examination, ultrasound, drainage of fluid, and laboratory tests.
The earlier the cause is identified, the sooner appropriate treatment can be started. This may include medication, drainage to relieve fluid build-up, or treatment of the underlying condition.
If you notice unexplained abdominal swelling or other possible symptoms of ascites, it is important to speak with a doctor.
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Fazit
Eine präzise Diagnose ist entscheidend für die richtige Behandlung
Aszites ist oft ein Symptom einer schwerwiegenden Erkrankung. Eine gezielte Diagnostik, bestehend aus körperlicher Untersuchung, Ultraschall, Punktion und Laboranalysen, ist daher essenziell, um die genaue Ursache festzustellen.
Je früher die Ursache erkannt wird, desto besser kann eine passende Therapie eingeleitet werden – sei es durch Medikamente, eine Drainage oder eine spezifische Behandlung der Grunderkrankung. Wenn Sie eine unerklärliche Bauchschwellung oder andere Symptome von Aszites bemerken, sollten Sie daher nicht zögern, einen Arzt aufzusuchen.
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